My wife got into the car today and went to adjust the rearview miiror and it came loose from the glass. Does anybody know how to fix it or does it have to be taken to the stealership??

 

Not sure what year your car is, but if it's still under original warranty, you're covered, and any dealer can repair it. Even if it's (not too far) outside of warranty, it's amazing what a smile and a pleasant-but-firm request can accomplish with a service writer...
Lee

 

If is is not under warranty and the dealership wants too much to fix it, you can pick up a cheap kit to fix it at any automotive store. Good Luck

 

I think there's a metal button glued to the glass and then the mirror "clips" into that. What's separated from what?

 

There is a metal button but how do you get it off? Knowing my luck I'll break it if I don't know how to release it.

 

If the metal button/plate is still glued to the windshield your mirror should slip back over it, slide down and stay in place. If the metal plate has seperated from the windshield, and is in the back of the mirror stalk, then you need to slide it out and reglue it to the inside of the windshield. Auto parts stores sell this windshield glue, just be sure and mount it in the correct position.