For instructions on registering DLL files in Windows 98, XP, Vista, 7:
If you have a bug related to files * .dll and * .ocx, you must:
1. Check for the required file system. Files * .dll and * .ocx, as a rule, should be located in the system folder C: \ WINDOWS \ system32.
If the files are present, you need to register them.
- Press the "Start / Run" or press the key combination Win + R
- Enter regsvr32 dx9.dll (example: regsvr32 d3dx9_26.dll)
- To restart a computer
How to download free dx9.dll?
2. If the required file is not present, look for them on the site, download and copy the folder C: \ WINDOWS \ system32 and register as stated in the first paragraph.