Let us assume that you have powered up your computer but nothing has happened. To be clear the fans and the processor within your computer may well have switched on but the hard drive was not identified in the BIOS and on subsequent checking you find that the hard drive is not spinning up at all. This is best determined by placing a finger on the side or top of the hard drive very lightly and feeling for the vibration associated with the spinning motor inside the hard drive.
It is wise before going any further to rule out the possibility of a faulty power or signal cable, and also the possibility of course that the power and/or signal cables are not properly plugged in at either end.
Once these have been ruled out and you are satisfied that the drive is not spinning up then you can be certain it is a job for a specialist hard disk recovery company.