It's very easy. I paste a little plastic piece in the little white lock site (at the unlock position). Just put it on. You don't need any more. The plastic piece doesn’t need any metallic contact.
These cards are so cheap that I suggest you replace it and transfer any files from the broken one to the new one (or better still transfer the files NOW to your PC).
Ray Peate
March 2007
I can answer this question...
The little white lock on my pqi 256 sdmmc broke off, can't save files?