[ubuntu] Flash drive became read only ...

I don't know. But I suggest that you do it the safe way and start with a backup.

Then you can look more into the problem. I suppose that you have been writing to these flash drives many times before, so something unusual has happened.

- Have you tried in another computer?

- Maybe try with some other operating system (a live Ubuntu system, free from possible damages, another linux distro live, or Windows)?

- Please post the output of the following commands, when the flash drives are coected, and check for the permissions

df
sudo lsblk -fm
ls -l /media
ls -l /media/$USER