Flash drive not readable by this computer

I got this error when inserting a flash drive: "The disk you inserted was not readable by this computer." I tried to put it on two old PCs at work and I'm either even worse at using PCs than I thought, or it flat out didn't acknowledge that I put anything in.

It isn't my flash drive. The owner had some files I needed saved on there, but I don't want to accidentally erase anything else that might be on the flash drive. These files are important so I'm really concerned...

I opened Disk Utility since I saw that was recommended when I did a Google search, but this is what it shows... I can't click verify.



I tried to restore it to another USB and it said:
"Restore Failure
Could not validate source - error 254"

Please tell me the data is not lost forever...

(sorry if this is the wrong forum)

 

Yeah, didn't work... but for some reason it did work on someone else's computer and I managed to get the files. I'm still really annoyed that it isn't working because it just doesn't make any sense, but I guess no damage done...