My rearview mirrow got snapped off my windshield and it left a small black plastic tag on the windshield. Do I have to relace the whole setup or will I be able to glue it back on with a special glue?
You’ll find a special glue kit in any auto parts store for this purpose. It’s a cheap and easy fix.
Hint: Trace the position of the mounting tab for the mirror outside the windshield with a grease pencil.
Then when the new tab is installed, wipe the grease pencil off the windshield.
Maybe I’m misunderstanding, but if there is a metal piece left on the windshield, that’s what is glued onto the windshield and the mirror fits over that. So if what broke is the stem on the mirror itself, you can’t glue that and the piece needs to be replaced. If so, check with the dealer to see if just that stem can be ordered. If the metal piece on the windshield came loose, then never mind, and you can use the mirror adhesive for that but do as suggested to mark the location of the tab before cleaning it off.
Good point by @Bing
You could stop by an auto glass shop for an estimate. Even if you don’t use them for the repair, that should give you the information on what needs to be done. If you do need some glue work, they might do a better job than you would.
The OP states, “and left a small black plastic tag on the windshield”
They switched from steel to plastic mounts for rear view mirrors years ago.
And if the mirror snaps off, it usually breaks the plastic mount.