Cannot turn off ReadyBoost from USB, disk appears to be read-only

Question

I recently started using ReadyBoody on my Sandisk Cruzer Edge 16GB USB, and when I needed to copy files into the USB, I could simply go right click USB > Properties > ReadyBoost > turn off ReadyBoost.

However, now I have a message this device is mounted read-only. This usually happens with write-protected media or when BitLocker Policy's setting has prohibited write-access ..." but in actual fact, I hadn't done any write-protection, nor turned on BitLocker.

I can't format it (though, I wish I could, if I could), because it says it is write protected, and I have tried formatting through Safe Mode with Command Prompt too, no success. Also have tried using PNY UFD UFIX II Formatting tool, with no success.

I have also turned off BitLocker settings so that it allows writing, but to no success. I've also seen a couple of posts regarding going to regedit and changing that values in Storage Drivce Policies and usbstor to "0" but with no success.

My USB has no write-protection button/ switch on it either.

The strangest thing is I can see the ReadyBoost Cache file on my USB. It's not an issue of turning ReadyBoost on or off (so please don't start going on about how useless it may be like some other threads), but an issue of reclaiming my USB.

Anyone that can help me reclaim my USB? Thanks all