how long ago you formatted the drive. If it's been in the last couple of days rather than months, there is hope for some of them at least. Otherwise, you can pretty much figure on them all being overwritten by now. If they were on a partition that you haven't written anything to since then, the chances are better.
Here are some shareware and freeware programs you can try. The shareware ones will tell you what can be recovered, but until you buy the product, it won't do anything else.
DATA RECOVERY TOOLS
I got a nasty virus on my computer over last summer, and eventualy had to format my hard drive. Of course being the idiot that I am I didn't back up anything before I panicked and formatted. I lost a lot of really important pictures and some less important music files, is there any way I can recover these? A friend of mine gave me a program called Spinrite, but I don't have a clue how it works or what to do with it. Can any one help?