TromboneChat

I got my trombone out of my case this morning and I saw that my slide lock was stuck and I couldn't move my slide.

Any advice?

Stuck in which position? Is it screwed in too tight? Or is it jammed with the tooth on the slide?

Sounds like it might have gotten bent somehow, or maybe just pushed too far around, so now it's got a lot of friction keeping it in place. Maybe try tapping it lightly with a rubber or rawhide mallet.