Hey there, rebzferbi.
So I assume that this is not your OS drive if you say that it's not detected?
You could give it a try with a different SATA port and cables, to see if the same thing happens, because this could easily be a faulty port or a cable. It would be even better if you could try it with a different computer as well. If you have no data to recover and you manage to get a computer to recognize it, you could download the HDD manufacturer's diagnostic tool and run the tests to see what's the situation with the HDD.
However, if it does not spin at all, there's no hope that it would be recognized. If this is the case and you have data to recover, you should go for a professional option, such as a data recovery company.
If you...