a quick search (
32MB-SD-Card | Flickr - Photo Sharing!) tells me that the locking switch is only evaluated by the card reader which means, theoretically, the card can still be written to if you find a card reader that ignores the position of the switch. I don't know if this theoretical fact is actually useful though, as it would probably depend on altering the firmware or software of your card reader.
alternatively, I found what appears to be a fix (
How to Fix a Broken Lock on SD Cards: 5 steps - wikiHow) for a broken SD card lock. You might try it out and see if it works (and then probably buy a new, not-broken SD card once you get the files off the broken one).