Vista Tutorial - .NET Framework Problems

Everytime I try to open a game or something requiring .NET Framework I get this error message:

To run this application you need to install one of the following applications:

.NET Framework v2.0.50727

I already installed this, and it errored, and it did not appear on my add/remove so I couldn't uninstall it. So I tried deleting it manually through the Framework folder, which Vista won't allow me permission to do. So i did the next best thing and ripped it out onto my desktop. I tried to reinstall and the installer claims that 2.0.5 is already installed, and I can't even reinstall 1.0 or 1.1 because it errors, and I can't install 3.5 because it thinks there's a prior version. So now i'm stuck with three folders on my desktop I can't delete, no .NET Framework and seemingly no way of getting it. What do I do?

Check these service:
Microsoft NET Framework NGEN v.2 is set to MANUAL

if you have unlikely you have to correct it + restart

If no help try this:
Run cmd.exe with administrative previlliges (right click on this file as admin) and type

%windir%\Microsoft.NET\Framework\v2.0.50727\ngen.exe update

and wait for momemt

I tried the cmd and got an error message stating:

C:\WINDOWS\Microsoft.NET\Framwork\v2.0.50727\mscorwks.dll could not be loaded

And an error on the cmd saying Unspecified Error <Exception from HRESULT: 0x8004005 <E_FAIL>>

Do you have this folder which I showing in attached image?If not or you have not much files there for you only leave System Restore - undo
or Repair Install For Vista

Thanks for all your support. In a blind moment of luck I discovered that the auto update had tried to install .NET Framework before Service Pack 2, so I system restored and downloaded a standalone which installed and then Auto update cought itself up.

Regards,
Cypher