Hi my name is ***** ***** I will be the expert working with you today to help resolve the problem you have posted.
This error pops up if the format of the saved file is not compatible, corrupted or broken in that case the computer says you need to format the usb drive as it will be ready to save new files as per windows or mac computer you are using to read the usb flash drive.
you may try connecting to another computer and see if it reads.
as i said in my previous answer the if a file didnt get saved correctly to the flashdrive or its corrupted or broken the computer will not read, I asked you to check on two different computer just to make sure the flash drive is functional and the file is corrutped.
you may try a tool which can help you fix the file if the file is in recoverable state i do no gurantee that it will recovery 100%
Click on the link below.