Time Machine messed up backup drive Help!

I have an Western Digital MyBook 600 Gb External HDD and i just went to see if i could use time machine on it and it asked me to re partition and erase the drive, by accident i clicked okay rather than cancel.

It started to erase the drive so I freaked out and tried to quit system preferences, no good so without thinking twice I pulled the cable for my external HDD to cut the connection. I then re connected it and Mac OS X didn't recognize the disk and said it was un-readable.

It's my family's external HDD that everybody uses, if any data is lost i am screwed. There is work backups on it, photos, Mac backups...

I am using drive genius 2 to see if i can repair it from that but i need help!