Changing the rearview mirror glass on a Volvo is a relatively simple process that can be done on your own.

One of the most common reasons for the glass to loosen is that the glue that holds the glass dries out and loses its grip over time. This may be due to the glass being exposed to high temperatures, for example via the defroster.

Another factor that can affect how well the rear-view mirror glass is fixed is vibrations and shocks that the car is exposed to while driving. If the glass is subjected to enough vibration and movement, it can gradually loosen from the mount, causing it to eventually fall off.
If you were lucky and managed to save the glass from falling to the ground, just glue it back in place, Vparts recommends using black glue.

We have some with convex glass and some with aspherical. Click on view products below to see which one you should have!

Remove the old rearview mirror glass from the mirror housing by angling the mirror in as far as it will go and using a tool on the inside to pry outward as close to the center where the bracket sits as possible.
We recommend using our demounting tool to avoid damaging other parts.

Once the old is gone, plug in the wires for the heating, it doesn't matter where you put the connectors. If your car does not have heated rear view mirrors (common on imported cars) then it is not needed.

Place the new rearview mirror glass against the attachment points, if the glass has plastic rails make sure these go into their slots first, then push in the center of the glass when you put it back in so it doesn't crack.

Check that the new glass is securely attached by gently pulling on the sides.