Yes, this can happen for various reasons. On the driver's side I had this problem - the door latch wouldn't work, or if it did, it would stick in the shut position. The culprit turned out to be not the latch itself but the plastic housing that the lock button goes in which had broken. On another occasion I had the problem that the passenger door mechanism would jam in the locked position. Generally after driving around for a little while it would start working again. However, it did so on an MOT test, which was failed because they couldn't get the door open. There did not appear to be anything wrong so with the door trim panel off I lubricated everything and put it back together. Then a few weeks later it happened again and took ages to unjam itself, whreupon I bought a new latch mechanism and put it in. It's been fine since. Nothing obviously wrong - probably just a bit too worn.
