How fragile is a Hard Drive?

Sad to say Nicky but hard drives are very fragile, since they slide around and got bumped that is a big problem the possibility exists that they are finished try them if they make a grinding sound and works thats a problem don't save important stuff on them they will finish crash soon, if they don't make any unusual sound they are ok. I lost several hard drives that way my worst scenario was my first 500 GB Segate drive if did not even got knocked in that manner it got a little know and a bit of shaking up it got the knock when it flipped over on my bed yes all soft sponge it was resting on a jersey i accidently pulled the jersey from underneath it and it flipped over and that was the end of it. What i can suggest is find out if it is possible to have a technician open it and asses the internal damage because i am still thinking of sending mine to the manufacturer. Because i need my stuff on it so if you need your stuff that is the only possible method to get it back.