I am unable to access my data because I keep being prompted to reformat my USB.
If I reformat it, I will lose all my data, and I don’t want that to happen.
How can I fix this? 
Sounds like you might have a corrupted FAT (File Allocation Table), which is why it’s asking for a format. Or the drive has gone bad.
If you cannot access your data because of the format message, you’ve already lost your data. This is a good argument for back-ups (or even back-ups of the back-ups), so try formatting it. If it works, great. If not, you’ll have to buy a new one.
if format completes you can try data recovery software. there are literaly hundreds of data recovery apps available some free some paid just find one you like and give it a try.
Usually when your system asks to reformat is due to logical errors
Use CHKDSK to recover files, if it fails the USB device may be already in error
If your USB prompts to format, don’t do it- you’ll lose your data. This error usually means the file system is corrupted. Use a photo recovery tool like Stellar Photo Recovery to create the image disk first and then format it. Once files are saved elsewhere, you can safely reformat the USB.
Avoid using chkdsk unless you’ve backed up the drive- it can worsen corruption and recovery may be difficult.
DON’T format it, you’ll def lose everything. what worked for me (my USB becomes RAW)was using this tool called easeus data recovery wizard, you can google it. i just scanned my usb before formatting, it found all my files & i recovered everything before wiping it clean. then i reformatted after backup n now the usb works like new 
give it a shot first!
