Try this http://www.cwc-group.com/am3bracket.htmlhttp://www.cwc-group.com/am2back.htmlhttp://www.cwc-group.com/secketam2.html
I guess anyone of these is compatible with your mobo
Hope it helps
From what I gathered of your description of the problem, I think the Back Support plate (Backside of the Mobo, a steele plate is screwed to the Front side bracket )
I guessed both are missing, the back support plate and the oval-ish plastic perimeter sort of wall around the processor socket in which we mount the standard HSF (Heat Sink Fan) right?
Well, anyways whatever is missing in that set you can find in the above given links, as a matter of fact if something else is missing, you'll be able to find it on that site too, small spares, fixtures, mounts, etc etc