Hello, Swadian noble123.
Rgl_config.txt file should be located at My Documents/Mount&BladeWarband. That is not the installation directory of the game. Please check there and delete the rlg_config file to force the game to create a new one.
If that doesn't work and if you have the game on steam: Go to your Steam library, right click on M&B:Warband, select "Properties", click on the "Local Files" tab and then click on "Verify integrity of the game cache". That should let Steam re-download corrupt files. If you do not have the game on Steam, reinstalling could solve the problem.
Rgl_config.txt file should be located at My Documents/Mount&BladeWarband. That is not the installation directory of the game. Please check there and delete the rlg_config file to force the game to create a new one.
If that doesn't work and if you have the game on steam: Go to your Steam library, right click on M&B:Warband, select "Properties", click on the "Local Files" tab and then click on "Verify integrity of the game cache". That should let Steam re-download corrupt files. If you do not have the game on Steam, reinstalling could solve the problem.