remove the plastic cover inside the door (1 phillips screw to remove behind small cover) and you will find a nut to undo.knock or turn it anticlockwise and disconnect the wire(if electric mirror) then remove and replace mirror,add nut and tighten.
steve
April 2010
I can answer this question...
How can I fix the driver's side mirror on my 2002 Fiat Punto 1.2?