My GF just stole all of my blonings and broke up with me. Can I sue for lost property?

You can call the police and report the theft. 

If she stole your stuff report it to the police. That is a crime.

Yes. It’s called small claims court. Ever watch Judge Judy? 

You can sue but you will need to prove your GF stole your stuff with more evidence than your accusations.  Typically that is extremely difficult to determine what was yours or hers and what was and wasn't a gift.  Do you have any text messages about the stuff that might support your claim?  That will serve as good evidence in small claims court.

You can take her to small claims court. You have to be able to prove she took your possessions and their approximate value.

Ask judge judy