1. Correcting the Terminology
It is highly probable that you meant d3dx9_30.dll.
Corruption or Deletion: The file may have been accidentally deleted, corrupted by a system crash, or quarantined by antivirus software. How to Fix "d3dx9_30.dll Missing" Errors
The system is telling you that the DirectX 9 runtime is either missing, outdated, or corrupted. Even if you have Windows 10 or 11, which come with DirectX 12 pre-installed, Microsoft does not include legacy DirectX 9 files by default. Hence, older games that specifically call d3dx3_30.dll will fail.
The best way to fix this is to let Microsoft handle it. Don't go searching for random DLL download sites—they can sometimes bundle malware with their files. Download the DirectX End-User Runtime Web Installer : Visit the Official Microsoft Download Center to get the installer. Run the Installer