Hi
Normally you would be able to see the drive and copy all of the data to another location, i.e. an external hard drive after booting to the Ubuntu disk.
Since it doesn't see it, there's not much you can do.
You won't be able to reinstall to the disk either unless the computer recognises it.
The problem is that unless something sees the drive you can't do anything to it, like running check disk or installing to it.
If you put in the Windows install disk, and it sees the drive, then you should be able to fix it, by running a repair install and keeping all your data intact.
But you have to be able to see the drive to do that.
You can try downloading an .ISO file for the version of Windows that you have, with service pack one, and make a bootable install disk.
Official Windows 7 SP1 ISO Image Downloads
You will need to make a disk from the file using Imgburn.
The Official ImgBurn Website
Put in the disk and if it sees your drive, do a repair install.
Repair Install - Windows 7 Help Forums
But if it doesn't see your hard drive you're out of luck.
I don't know of any software that will recover an unreadable disk, there are places that do that by taking the disk out of the drive and reading it in some kind of machine, but it's very expensive.
I keep saying this but, Backup everything on your computer to a safe place not in the computer. If you only have a small amount of stuff you can use DVDs, most people will need an external hard drive.
Mike