Assuming you mean re-mount it to the windshield, try your local parts place for a kit that does the job. They are inexpensive but the directions must be followed to the letter. Or did you mean the mirror is broken? You weren't clear with your question.
Rear view mirror.
There should be an Allen wrench slot on mirror base
Rear-view mirror was created in 1911.
Rear View Mirror was created in 2011.
you go to ford servies centre
buy new mirror and glue then follow directions on the box
junk yard
There is a special glue that they sell for it at autoparts stores.
My friends 1995 Ford Explorer Limited does , the controls are on the rear view mirror
Remove the inside door panel. Remove the wiring harness. Remove the mirror retaining bolts. The side rear view mirror will come off.
YOU CAN PURCHASE THE ADHESIVE AT YOUR LOCAL AUTO PARTS STORE , BUT IS WISER TO BRING IT TO YOUR LOCAL AUTO GLASS SHOP. THE SAVING FROM DO IT YOURSELF IS AROUND 3 TO 4 dOLLARS .
Depending on and if the mirror holding clip came off the windshield. If it came off windshield you will need to buy a rear view mirror installation kit. Follow instruction on kit to be install.