Can't unlock truck

Have a '75 Duster. I believe I damaged my trunk lock. I closed my trunk and now I can't open it up again. The key will go in and out of the tumble ok, the key turns fully with no binding, it just won't unlatch and release the lid. This is a Space Duster version, but the back panel is up and latched so I haven't been able to get in the trunk that way. Any ideas?