Have I lost my entire Windows drive and all the files?

I previously had Heron 8.04 installed. Today I decided to upgrade.

During the partition phase of the install of 10.10 it asked me what portion of the drive I should use. There were a few options:

• Drag the partition size to indicate what I wanted to use
• A button that said use entire partition
• A button that said use entire drive

I selected use entire partition as the Windows partition did not appear on the screen I assumed this was just displaying the existing Ubuntu partition.

After install I think I have wiped my entire Windows partition, I can't see it anywhere.

I would appreciate some advice as to find if it really is gone forever (My stupidity I didn't back up my Windows partition which includes 3 years of baby photos).

UPDATE: Thanks all for your great answers. I read on a forum last night about Active Partition Recovery. I didn't realise it was a commercial product, so the demo doesn't let you recover, but it did allow me to see that the whole partition still exists somewhere on the drive. It even let me see the individual files.

As suggested I have stopped doing anything with the drive until I can give Testdisk a try. If this works I will confirm it in a separate answer for future reference.

You can see all of your partitions by running System->Administration->Disk Utility. Once the window opens, click on your hard drive on the right hand side. Have a look at the partitions.

If one of the partitions is an NTFS partition, it is likely that this is your Windows partition. If it is there, you can access the partition from the Places menu.

Until you know what happened, stop using the computer. Even if you did re-use the partition, there is a chance you did not overwrite all of the stuff on it and you may be able to recover. But the chance of recovering goes down the longer you use the partition!

All the work you do to recover should be from a bootable CD or USB key so you don't risk overwriting something.

Personally, I like the System Rescue CD as it bundles a lot of good stuff in one place.

Good Luck.