asalcedo wrote:
The inside rear mirror of my car has come unstuck from the windshield
glass.

They were just stuck together with some kind of glue, I assume.

Something similar to glass is now stuck and protruding at the base of
the plastic of the mirror. The same shape is missing from the
windshield.

What is the best way to fix the mirror back to the windshield? Is there
a special type of "glass" glue?

Yes, there is a special glue for this, available from Halfords and other
car accessory shops.

--
Grunff