I have a similar condition with My Ext Hd Iomega.
I was trying to backup my Disktom where it jamed and I turned the powed of , when I pluged my Hd in any computer sice then it keeps asking me to format my Hd. how can i get back my data
TestDisk, Data Recovery TestDisk is powerful free data recovery software! It was primarily designed to help recover lost partitions and/or make non-booting disks bootable again when these symptoms are caused by faulty software, certain types of viruses or human error (such as accidentally deleting a Partition Table). Partition table recovery using TestDisk is really easy.
NOTE If seeked lost file are still missing, give PhotoRec a try. PhotoRec is a signature based file recovery utility and may be able to recover your data where other methods failed.
PhotoRec is file data recovery software designed to recover lost files including video, documents and archives from hard disks, CD-ROMs, and lost pictures (thus the Photo Recovery name) from digital camera memory. PhotoRec ignores the file system and goes after the underlying data, so it will still work even if your media's file system has been severely damaged or reformatted.