I'm upset at my gf's parents for locking us out of the house
What did you and your girlfriend do before that?
I'm not sure we just can't get back inside.
Well you should definitely talk with her parents to find out what happened to make them lock you out. It's important to be able to talk through things with the family of your girlfriend.
I'll try, I don't know what they are upset about.
I'll try, I don't know what they are upset about.

Communication is always key in relationships, especially with romantic ones. Hopefully talking with her parents will help resolve the issue and you can all work through this! You deserve a great relationship with everyone.