Well, if you do not want to lose data from your read-only USB flash drive, then first you must recover your important data from your USB flash drive. You can try USB file recovery too, it will recover photos, videos and audio files from the USB.
Once, you recover important media files, then follow the below solutions to fix “read-only” error of USB flash drive.
First of all check if your USB drive has any switch lock or not, if there is any lock switch, then simply slide the lock switch to unlock position. Now check your USB drive.
If that also does not fix your problem, then you can run CMD command to fix read-only error of USB Drive.
I hope this will fix your issue.