I have trouble opening NMM for my New vegas game saying that it does not have the permission to write the game and I've been told that I should run as admin to open it, but :
Can someone please explain it to me how to do it ?
Also will this affect my Skyrim game as I've also have the game modded.
This is happening because you have New Vegas installed to a restricted location. (Program Files, maybe?)
To fix this, you'll just need to do exactly what it asked you to. Right-click your NMM shortcut on your desktop and select Run as administrator. To save yourself from having to do this all the time, right-click the shortcut, select Properties, go to the Compatibility tab, tick Run this program as an administrator, and then click OK.
If you torrented the game, that would be the obvious issue. If not, though, try reinstalling it to the directory NMM looks for.
