Chkdsk

I got out a USB drive that I will bring along on the trip. I had previously used it in Europe and elsewhere and there are 600Mb worth of videos and photos on there.  As well there is over a Terabyte of unused space for more trips.  I moved it from one machine to another and the second one said "corrupted file system disk drive unreadable".  When I put it back the problem was still there.  All is not lost. Type CMD to find the Command Prompt.  Right click it and select Run as Administrator.  Then use the Chkdsk command in repair mode eg chkdsk /F E:  where E: is your USB drive with the errors.  Fortunately for me the system files on the drive were repairable and I have not lost anything.  Many files were already copied to other drives but not all of it.  Always use the 'safely eject USB button" before removing any media. These drives can die for various reasons.

It was grim but then brought back to life