Relax.just goof around a little.Right click on the icon for autocad,and then click on properties.investigate the various menus and see what they produce.
The first thing is run a search in your main hard drive for your acad.exe .In the search ,it will have a little Acad icon.right click on it,and up will come the properties tool bar.
It looks like this.Then 
select the compatibility that you ran it in before,and click apply.