Broken Lock

[Subanez]

So I have a question:

I shut my driver's side door tonight, and when I put the key in the lock, I heard a light tinkling sound, like small glass had just broken. End result is that the driver's side lock doesn't move with the key. I have to lock the car from the passenger side (and yes, when I do THAT, the driver's side door locks.)

Any idea? Did the lock bust? How much to replace?

As a side note, I haven't posted for a month because my computer died, so, here I am back again!

-Kevin