I think the antenna is broke or something... it has to do with the back window I think... is there a easy way to fix or replace it? Thye am don't work on my radio... fm is fine...

Check all the fuses. There needs to be power going to the antenna amplifier module in order for it to work. The amp itself is in the trunk, mounted to the underside of the package shelf.
Inspect the connections at the glass as well. FM can get through a poor connection that won't allow AM connectivity.