Recuva (freeware)

I downloaded Recuva, installed it and attempted to recover a deleted file on my 64 GB flash Voyager USB stick. from Corsair. Although I did not do anything since since, I can no longer store any files on it. The message reads that the stick is write-protected.

I tried all kinds of things

1) I started from safe mode with command prompt: But my USB-Stick was not recognized

2) I entered a registry key but everything

to no avail

Can anybody help? Thank you.