Blue light comes on wd detected...

Hello,
I purchased a wd 320 external hhd . i went traveling round europe took heeps of pic..... and backedup all my ipod music..... it worked for 3 months now i plug it in the blue light comes on it spins up, my devices manager shows WD under drives the computer rings a bell to say its detected somthing but it wont auto load or show up in my computer i have used it on an xp windows as well as vista but it still ran sweet. i have since bought new cabels thinking the cabels broke but stil no good. i tried on 3 other laptops no good. and disconnecetd the charger from the wall thinking we had a surge protection on the power circut still didnt help. can u advise of a missing dll file or program i need to make it work..... running vista home..... sony vaio....... model vgn-n27gh please help i need my pics and music