How to recover data from an external HDD?
As a last resort you could try the old "ziploc and freeze it" trick. I've seen it work before.
Sure. There are companies that are specialized on that. It costs, though.
OTOH, it is the ONLY way to work around a mechanical issue - they actually OPEN the disc, and get it working (or read it out using special equipment) in a clean room. At home, sorry, you have no chance.
Look up on google under "disc data recovery". Expect to pay. By the Gigabyte.