Before you install CoD4X, you have to update your game to the latest official     version, which is 1.7.

 If you own the Steam version, this is already done for you. Otherwise, please   follow the instructions below.

          First, update the game to 1.7

1. Download the 1.6 and 1.7 patches from here! (cod4x.me)
2. Install the 1.6 patch first as administrator
3. Then install the 1.7 patch as administrator
4. Launch the game and check in the bottom right corner if 1.7 is displayed as version

                 Once you’ve done that, you can move on to installing CoD4X!

         Install CoD4X (1.8)

1. Download CoD4X from here (cod4x.me)
2. Extract the zip file to your Cod4 installation directory
3. Enter the extracted folder
4. Run install.cmd. You might have to run it as an administrator
5. Launch the game and check in the bottom right corner if CoD4X is displayed

After all that! Check if the first button in the list says Auto-Update (ingame), if so Do it!

As many Steam gamers have noticed they got an update for Call of Duty 4 – Modern Warfare. This update was kinda breaking the game completely.

Here is how to fix this patch:

Download the file from this site here

This is the main and original game executable from CoD4 1.7.

When done locate your CoD4 installation, there are 2 ways to find it. If you know where you Steam folder is you can find it on this way:

Open a new Windows Explorer Window. Go to your “Steam” folder (Which is likely in “C:\Program Files(X86)”) then click on “steamapps” then “common” and then “Call of Duty 4”. Here you got to your CoD4 folder.

Just in case you didn’t find your CoD4 folder here is another way:

Open the Steam main window, then click Library, Games. Find in the left list “Call of Duty 4: Modern Warfare”. Rightclick the game and choose properties. In the new window click on “Local Files” and then “Browse Local Files”. Now you should be in your CoD4 folder.

Since you have now your CoD4 folder locate the file iw3mp.exe. Right click onto it and chose “Delete” and confirm it.

Now go to your before downloaded file then drag and drop it into your Cod4 folder.

Here you should be done with the guide. A reinstallation of CoD4X shall not be necessary as it remains installed even after the Steam update. It just does not activate in case the “iw3mp.exe” file gets replaced

Would you like to fix your Punkbuster files since you either can’t install them trough steam or like to fix them cause the files you found won’t work? Well here is the fix Down Below!

Go to this link: Here

Download and Extract the Folder called PB,

When done locate your CoD4 installation, there are 2 ways to find it. If you know where you Steam folder is you can find it on this way:

Open a new Windows Explorer Window. Go to your “Steam” folder (Which is likely in “C:\Program Files(X86)”) then click on “steamapps” then “common” and then “Call of Duty 4”. Here you got to your CoD4 folder.

Just in case you didn’t find your CoD4 folder here is another way:

Open the Steam main window, then click Library, Games. Find in the left list “Call of Duty 4: Modern Warfare”. Rightclick the game and choose properties. In the new window click on “Local Files” and then “Browse Local Files”. Now you should be in your CoD4 folder.

Now Move the Folder Called PB to the main CoD4 folder 

Should look Like this:

Now Just run The Game and have fun!