IMPORTANT: I've tested this procedure over Kingston Datatraveler G4 64GB. Before repairing the pendrive, you can try to save your files on other location. You are solely responsible for the result, data loss or of any damage it may cost to your device or computer system. You are solely responsible for backing up or saving all of your files or data.
One day when you plug your pendrive on your PC, it says that the device is on read only mode. You can't add or delete any files.
Probably you have tried to format the unit or edit the registry because you haven't read something on the forums. Anything of these have worked for you.
May be you need this program: Restore.exe. I got it on www.apacer.com. Click on this link: http://eu.apacer.com/support/download/result/3,8,0,
Download USB 3.0 Repair tool.
Uncompress zip file.
Once restore.exe is running you can see the buttons Format and Restore. First of all, you can try to format the unit, but I supposse that it doesn't work. Later, press on Restore button and wait until the process is complete.
The pendrive appears empty on your file explorer. Now, you can create one file on your pendrive and work normally.
I hope this works for you.