|First things first.. What kind of drive is this? External or internal? USB, etc? Can you also provide the model number? |
If its an external drive I would start with testing out the power adapter to ensure its outputting voltage. There are also ways to get your hard drive out of the external casing (should it be external) for further diagnostics.
If this was internal, I would test it with another working molex, whether that be on the same PSU or another PSU.
Either way, first need to determine if you can power on that hard drive, because without getting it to power on, the best bet is taking it to a data recover center, which will be costly. If you can get it to power on and be seen by the BIOS, try to access it on a workstation. If not accessible, a RAW data recovery will need to be attempted to recover the data.
Will be able to assist more with more info! Thanks.