ext hdd not regognised

My pc works just fine and I want to add old external HDD in to my PC. It didn't work at all even in BIOS didn't detect any new drive plug in. So I try putting it back to External and it work perfectly fine!?! All SATA cable is new and is working just fine, all SATA slot is useable ( tried with...

my ext hdd stopped working, it shows like localdisk g: i tried fixing with chkdsk, many softwares, disk managment but the problem is when my ext hdd is plugged in, chkdsk, various softwares, disk managment stopped working i tried to format it also but does'nt work either. is my drive dead? what...

Kindly advise: I have had my Seagate 3TB HDD for a few years, no longer under warranty. The driver suddenly dissapeared from file manager (Windows 7). I can hear the drive running, but the light does not come on. I have tried to connect to another PC and the same happens. So there is power...