AFAIK this needs to be done by a specialist company where it'll cost a crapload of money.

http://www.ontrackdatarecovery.co.uk/

You go to your backups, and restore from those.

Motor failure is a really big problem. In most modern drives, the motor shaft is used to mount the platters on.
If the motor goes, you can't just unbolt it because the platters then need to be realigned.
Their alignment has to be extremely precise - head clearances can be a lot thinner than a human hair.

Buy an identical drive.

Make a clean room - go into the bathroom, turn on the shower very hot. Let steam accumulate in the atmosphere and then turn off and let cool. The cooling steam will clean the atmosphere.

Now, after ensuring you're in clean clothes that give off little dust, take a watchmakers screwdriver set and take apart the old and new drives, swapping the platters between the two. If you're lucky and skillful, when you put them back together it might work.

Depends on the model, though, and you'll probably have to read around a lot, too.