I have no idea why you want to revert to Lion, and this is getting very confusing since the information you keep giving is very unclear. I'm tempted not to post anything more, but I'll give this one more shot. This would be to get back to 10.8, which you appear to have been running before you erased the drive.
http://support.apple.com/kb/ph11273
Getting back to Lion from Mountain Lion is either impossible or extremely complicated. I don't have an answer for that one.
But you can get to Lion from Snow. If your Mac is from 2009, then the 10.6.3 retail disc or the disc that came with the computer should install. And then, maybe, you can find the Lion you originally purchased registered to your Apple ID at the Mac App Store. But you should know that if you go this route, you will lose all your user data, since the drive will need to be completely erased before installing Snow. You should make a backup on an external drive before doing this, that is if you haven't already lost all your user data.
That's all I know. Perhaps if you bring your Mac in to an Apple Store they will help you out there.
EDIT: Read this also. Instructions to downgrade from ML or LIon to Snow
https://discussions.apple.com/thread/4724271?answerId=20968586022#20968586022
Message was edited by: WZZZ