i am using auto cad 2008 so i download 2010 trail an open one of my drawings in that program an now i am trying to open it back into 2008 it will not go back

I'd recommend that you post in a AutoCad specific forum. Try here: AutoCAD Forums - Powered by vBulletin

This one is directly linked to our site. We generally don't help with Auto Cad.

why can't my pc be able to download anything?

why cant my pc be able todownload anything