Here is a 3 ways to save you hard drive article, which adds to your knowledge but requires you to read and do some work.

For the easy way you can try Ontrack's Easy Recovery. The Data Recovery Wizard helps you determine which version to get by asking you what is the media (hard disk, cdrom, etc.), your operating system, and the problem.

This utility, at least the old version, works great, I've tried it before when it was still called Tiramisu and I recovered files from a disk that I had both fdisked and formatted.

P.S. You'll need to purchase it or get a warezed version to actually recover the lost data; you will only see what you can recover with the free versions.