I don't know which DirectX installer program you are attempting to use, but there are two
versions.
- The DirectX Web Installer is best used on machines with a new Windows installation, or one
which has never had DirectX updated. There have not been any 'new' DX files since 2010, so
this generally is not useful if DX has been updated previously.
(Garry's Mod uses one of the last DX9 files - d3dx9_40.dll, which does not install with Win7)
The Web Installer will install any 'missing' DirextX files, but does not overwrite any existing files.
Download DirectX End-User Runtime Web Installer from Official Microsoft Download Center
- The DirectX Redist (June 2010) installer package is the better option if there are any corrupt DirectX files, as this installed overwrites all DirectX files.
- This installer first 'unpacks' the DirectX files to a location of your choice (you can create a new
folder on the desktop and unpack to there, as this folder can be deleted after installing DX).
- Once the files are unpacked you need to open the folder and find the DXSETUP.exe and
run the final installation from there.
- If you still get an error...
R/click on the DXSETUP.exe and go to Properties.
Click on the Compatibility tab and tick the box next to 'Run as Administrator'
(this may happen if you are running Windows from a non-Administrator User account with limited 'permissions').
- Try installing from the DXSETUP.exe again.
- I suggest rebooting the machine after reinstalling DirectX.
Download Details - Microsoft Download Center - DirectX Redist (June 2010)
- If you continue to get error messages when trying to install DirectX using the Redist (June 2010)
you may need to try installing from Safe Mode.
Safe Mode is commonly accessed by tapping F8 while booting into Windows.
- If you have a problem accessing Safe Mode type - Safe Mode - into Help and Support on your
Start Menu for more detailed instruction.
It may also help to 'verify the game cache'. This is done from your Steam account.
- Go to your Steam Library and R/click on the games title. Then click on Properties.
- Click on the Local Files tab and select Verify Integrity of Game Cache. It may take
a few minutes for Steam to verify the games files are not corrupt.
- Also check the Steam support pages, if you have not already.
btw - You said 'little boy'. This game is more like a modding toolbox where you make your own fun than a 'scripted' game, and has a somewhat steep learning curve, so I hope not too little/young.
.