Try a calling a local double glazing company or two, they may be able to tell you if the hinges are replaceable or not. If the door is more than 10 years then the chances are the fittings may have changed and become obsolete.
Had a lock mechanism in the front door go. The main bolt worked but the small sliding bolts at the top half didn't move. A local firm fitted a new internal mechanism and now have a 5 point lock insead of the older 3 point lock. Took around an hour and �90ish