I had vs2010 ultimate then I downloaded 2012 RC. It was working well at the beginning then at some point .net framework get messed up so I uninstalled both 2012 and 2010 (maybe I have manually deleted some folders too). Now I re-Installed vs2010 ultimate and the problem is none of the standard library files exist I figured so as I can't include any of them.
Any help how to fix that?