OK, SO, After a long time I downloaded Skidrow mw2 torrent, but the thing is I get the same exact error I had before, It's called IWNET_INVALID of course I did download and run "Install IW4M.exe" but still even after that I get the same error, also another thing is that when I click on iw4mp.exe it does not ask for my username nor the password, what's going on...?

You have to run your game with the LaunchIW4M.exe (check your startmenu or %appdata%/iw4m)

Launch the game from start-play iw4m, not iw4mp.exe

THANK YOU! I cannot thank you enough I've been HOURS looking for a fix!

Aaaaaaaaaaaaaaaaaaaaaaaaaand it stopped working, now everytime I run the "play iw4m" it goes to not responding, well sweet sweet broken game huh?

odd. delete your caches.xml and run it again