How do I dis/en-able write protection on USB flash drive with Windows Vista

I have an unbranded (I know! Iknow! – now) flash drive that suddenly has become write protect. I have read all the suggestions about how to fix it. The closest was when in desperation I tried an XP solution where I had to change a 0 to 1 or somesuch in the Storage Control Policies. Going great guns until I got to Storage and the was nothing there.

Can anyone help please?

PS: Don’t tell me to flick the switch on the flash drive – there isn’t one.
And if it helps I was able to copy all data off drive, just not able to write to it