Accidentally deleted partition on external HD

Hi there, im stressing out big time and would really appreciate any help.

I was just formatting a computer and had my external hard drive plugged into the USB and mistook it for the on board HD when I was installing XP and accidentally deleted the partition on the external hard drive. (I didn't realise there was one)

Now when I plug it into my computer it is recognised but doesn't come up under My Computer.

I ran compmgmt.mscfrom the Start menu and located it under storage except it says "Uncallocated". Im pretty sure all the data is still on there 'cos its still taking up space but I can't get to it.

I tried making a new partition but this requires formatting the drive.

Any ideas? I really can't afford to lose this data!! Argh!

Thanks