I did this once. DO NOT DO ANYTHING ELSE TO THE DISK!!!
Try the free tool here to see if it can recover your stuff: http://www.runtime.org/data-recovery-software.htm
The free trial/demo will tell you what it can recover - then they'll want $80 (US) to actually recover it.
I've tried the free stuff available on the web and found it very difficult to use.
When it happened to me, I tried the free stuff and gave up - then I tried the above software and have stuck with it for the last 8-9 years.
I've been looking for a good tool like that to recover volumes or partitions thanks usasma for posting that i'll give it a try and if i like will buy it.
I've had (very quick!) success with MBRWork for drives with lost partitions in the past, some years ago I used RecoverMyFiles 2 or 3 times, it was $60 then, I think - not uncomplicated to choose the correct scanning method for the problem in hand the first time around though but once you get the right scan, that's all forgotten. Hopefully the help will be a little clearer by now.
Run the program,in the list you can see all the hard disk even the ones with deleted volume.
So i select the one with the deleted volume,i right click,click create,apply,restart,and the hard disk is back to life with all the data inside,programs,photos etc.