The prompt asking you to format the disk before you can use it means the computer cannot read the small structure that describes the file system. It is not a statement about your files. Refuse it, put the stick away, and the folders can usually be rebuilt from what is still sitting on the flash.
Refuse the format prompt and the price is published. Cards and USB pen drives are £250 + VAT, fixed in writing after a free diagnostic that closes 2 working days after arrival.
That message means Windows cannot find a file system where one ought to be. It is not a verdict on your files, and on a stick that was working perfectly an hour ago they are usually still sitting there. Which of the six below you have decides whether this is an afternoon of software or a chip-level job.
The best position on this page by some distance. The controller is presenting the flash correctly and only the small structure describing the file system has been damaged, which on a pen drive is a matter of a few sectors. The data behind it is generally intact and the job is software from beginning to end.
A stick reporting eight megabytes when it should report sixty-four gigabytes has fallen back to a safe mode inside its own controller. The flash is no longer being presented to the computer at all, so nothing you install on the machine can reach it, however confidently the download page claims otherwise.
The device enumerates far enough for Windows to give it a letter and then cannot deliver a capacity. That is a controller or power fault rather than a file system problem, and the way in is to read the memory itself and rebuild what the controller was supposed to be doing.
Removing a stick mid-write catches the allocation tables halfway through an update, so the directory says one thing and the tables say another. Files written that week are the ones at risk, everything older is usually fine, and a second copy of the tables normally survives to be compared against.
Same prompt, same answer, and the temptation is stronger because the device is insistent and the next job is waiting. Formatting in the camera writes a fresh structure straight over the old one. Take the card out, put it somewhere safe and use a different one until this is dealt with.
Most modern pen drives and every microSD card are built as one moulded block with the controller and the memory sealed together. There is no chip to lift off and read. The way in is a set of test contacts under the packaging, found by grinding down and probing, and that is chip-level work with terms to match.
When a computer looks at a stick it reads the very first sector of the volume, expecting a boot record: a small block of numbers saying which file system this is, how large the clusters are, where the allocation tables sit and where the root directory begins. Damage those few hundred bytes and every one of those questions goes unanswered. Windows has no vocabulary for that condition beyond RAW, and the only remedy it knows how to offer is to write a fresh empty file system over the top. That is precisely the action to refuse, because a new empty structure over an old full one is how a straightforward job turns into a partial one.
The recovery starts where the designers of these file systems anticipated the problem. FAT32 keeps a copy of its boot sector a few sectors further in, and exFAT keeps a complete backup of its entire boot region twelve sectors along. On a great many of these jobs the backup is intact, the volume is described again from it, and the files come back with names, dates and folders exactly as they were.
Where the backup has gone too, the parameters get worked out from the contents rather than guessed. The allocation tables have a distinctive shape and can be located by pattern. Directory entries are a fixed size with recognisable fields. Cluster size can be deduced from where file fragments actually fall across the device. It takes longer than reading a header and it produces the same result, which is a proper file system with your folder structure rather than a heap of numbered fragments.
A quick format does not erase your data, which is where the reassuring advice on the internet usually stops. What it does erase is the map, and on the smaller file systems used by removable media the map is doing an unusual amount of the work. Without allocation tables, a file stored in one continuous run can still be carved out by its signature, and a file broken into pieces scattered across the device generally cannot be reassembled correctly. Large video files from a camera are almost always fragmented. So the honest way to put it is that formatting will not empty the stick, and it will decide for you which of your files are coming back.
Every pen drive and every card contains a small processor between the socket and the memory, and nothing outside the device ever addresses the memory directly. Flash cells wear out with use, so that controller constantly moves data around to spread the wear, keeps a translation table mapping the addresses your computer asks for onto the physical locations they currently occupy, retires blocks that have gone bad and corrects errors on the way past. When it is working, you see a tidy sixty-four gigabyte disk. What is actually underneath is nothing like that.
Those translation tables live in the flash alongside your data. If they are damaged, or if too many blocks fail in the wrong places, the controller cannot work out what it is holding and stops presenting a disk at all. That is the stick showing zero bytes, or the wrong capacity, or asking you to insert a disk. No software installed on your computer can help, because the computer is not being offered anything to read. The route in is to reach the memory directly, then rebuild in software what the controller used to do: undo the way data was spread across the chip, reverse the scrambling applied by that particular controller family, correct the errors with the same scheme it used, and reassemble the pages into a disk image that a file system can be read from.
That is chip-level work. On older sticks with a separate memory chip it means lifting the chip off and reading it in a socket. On the moulded devices that make up most of what is sold now, and all microSD cards, the memory and the controller are sealed into a single package and there is nothing to remove. The only way in is a set of factory test contacts hidden under the packaging, exposed by carefully grinding it down and probed by hand, and on some designs those contacts are not usable at all. When that is the case you will be told so rather than billed for finding out.
Memory cards and USB pen drives are £250 + VAT, and that band covers the everyday version of this job: a stick that presents its correct capacity with a damaged file system, read out and returned with folders and names. The figure is fixed in writing after the free diagnostic, which closes 2 working days after the device reaches the bench, and the quickest a completed job runs from there is 2-4 working days.
Where the diagnostic finds a controller fault and the work becomes chip-level, that sits outside the guarantee and takes 50% of the quoted figure upfront, because the labour and the risk are spent whether or not the memory gives its contents up. The network line is exact: no fix, no fee all jobs except electronic and mechanical failures, chip level work, DVR and Forensic jobs. Everything logical keeps the guarantee in full.
Cards arrive from photographers working around Windsor and Ascot, from dash cams that recorded something on the M4 that somebody now needs, and from drone and camera work across the Berkshire countryside. Sticks arrive from the offices along the A329M and from people who carry one between a Bracknell desk and a London meeting twice a week. All of it posts easily, and a padded envelope with the device taped to a card so it cannot move is enough. Send it to Guildford Data Recovery, Building 2, Ground Floor, Guildford Business Park, Guildford GU2 8XH. See also USB stick recovery, memory card recovery and the full bands on data recovery cost.
Close the prompt, stop using the stick, and let the file system be rebuilt from what is still on the flash.
Almost every job on this bench arrived as a parcel. Tracked, insured post is the gentlest way to move storage that is already in trouble, and a box handed in around Bracknell, Wokingham or Ascot is normally on the Guildford bench the next working day.
Is the storage still bolted into a machine — laptop, tower, iMac, MacBook, rack server, a DVR under the till? Free it first and send the bare unit. Stripping hardware is not something this lab does, though it is ten minutes' work for any repair shop on your high street. There is a single case with no way round it: memory chips soldered flat onto the mainboard, which is how Apple Silicon machines and certain ultrabooks are built. Where the storage cannot be unbolted, there is no parcel to make up.
↓ Print the shipping & booking-in form (PDF)
The name on the parcel wants to be Guildford Data Recovery. Driving it over from Bracknell is roughly forty minutes on the A322 then the A3; posting it costs you a stamp and a day. Either way, a message goes out to you as soon as it is logged onto the system, and two working days later the diagnostic is finished.
Unsure whether something should go in the box? Ring 0800 689 0668 while the lid is still open, or work through the free online diagnostic and let it tell you.