How to know external hard disc is fault

[tropic22]

i don't understand why my laptop cannot detect my ext hdd. Usually the led showed its connection was ok. now..even the led light does not light up.

 

[jsc]

You can isolate the problem to either the laptop or the drive by trying to use the drive with another computer.

 

[Frequency44]

Does your HDD use an external power supply or does it receive power only via USB?