nProtect gameguard injects it's own DLL (npggNT.dll) in all running processes. Injected DLL hooks the several functions so it becomes impossible to attach to protected game process. Besides GameMon.des and GameGuard.des becomes invisible in process list.
I made a bypass for this thing and it's attached.
While the game is closed inject this dll into ollydbg, cheat engine or whatever program which you want to attach to the gameclient or GG processes. This dll protects your stuff from npggNT.dll is being injected. So now you can see running processes and open them.