Can't access my time machine backup

I changed the name of the little home icon in the finder sidebar. Once I did this and restarted the computer, everything went downhill. Why did I change the name....well my macbook pro was in the mac store for repair and the manager changed that icon name to Michael. My name is not Michael and so it annoyed me to see that every time I was in finder. When I went back into my mac everything was reset.

The home icon was named michael and is now named mikeguzman:


My last time machine backup does not show up in time machine. If i go in manually,
I get this message.


I spent more than 24hrs installing my photo library and music again on this machine. I don't want to do it again.

Any help getting to my time machine back up would be great.
Thanks

I'm running lion on an '08 macbook pro