My Book Essential Edition not detected by windows

Hello! my dad dug out an old My Book Essential Edition out of a cardbord box after moving, he gave it to me. i plugged it in to my server so i could use it as external storage until i realised i had enough space on my HDD. so i unplugged it and plugged it into my laptop. it worked and all. AVG wanted a restart so i restarted my PC so i could do a backup after it booted again, except for the fact that the external hard drive was no longer recognised. i tried switching the letter in disk management, but it says F:/ no media. after several restarts and differient cables nothing has worked. i only have 2 USB slots, and i have tried them both. any help would be apreciated.

My OS is windows 7 x64 bit my server is currently running windows XP x32 bit

i recently ordered an 500GB SSD, so i need this Hard Drive to Ghost my current HDD
(PS: my server didnt work the 2nd time either)