WD media player not recognising external hard drive

It's a Western Digital hdd and was working fine until a few days ago. I tried resetting the player and leaving it unplugged for a day and still no go. It works fine with my laptop though and my other hdds work ok with the player - although if I connect them after the malfunctioning one then it doesn't recognize them either and I have to unplug the player from the power supply. What I'd really like to know is if it's a problem with the player or the hard drive and if it's the latter if it's in danger of failing.