I had that happen to me earlier this year. Ended up having to have my mom come over with a set of keys to my house so I could get in there to retrieve my extra set of car keys.

I always fear doing that (not that I have very often) which is why I insisted my new car have one of those keyless entry pads installed. lol

It sucks to realize you've locked the doors AFTER you've already shut the door and can't do anything about it.