Write protect

I bought my usb sandisk when i was working in south korea. My problem about my usb is how to disable write protect. The Vault installed inside is corrupted. The time when it was vault corrupted is on write protect is enabled. I cant open vault now. I cant Delete and install new vault. (We know inside vault you can disable/enable write protect) I cant format whole usb. I tried everything cmd regedit apps etc but nothings happen. I just hope i missed something or new tecnique to disable write protect. I cannot replace it new one like said above i bought it 5years ago and it is not under warranty anymore… Thanks in adavance.