With the release of The Elders Scrolls Online I’ve decided to play TES IV Oblivion and TES V Skyrim to get into the atmosphere and storyline before I purchase the multiplayer version of the game. With the help of Steam Client I just clicked on the games in the game library and they started to download and install. The installation was completed within few hours and finally I started TES IV Oblivion and I got the system error saying that the program can start because d3dx9_27.dll is missing. That was unexpected, I never had problems with games installed on steam.
After some researches on the web I actually found why d3dx9_27.dll is missing error appears. It is because I just recently upgraded from Windows 7 to Windows 10 and as we know Windows 10 already has DirectX preinstalled, but not the 9th version. And since TES IV Oblivion is kind of old game it still requires the old version of DirectX. Long story short, to fix the d3dx9_27.dll is missing problem in The Elders Scrolls IV Oblivion you just need to download and manually install d3dx9_27.dll library from here: http://fix4dll.com/d3dx9_27_dll.
As for me I just placed downloaded d3dx9_27.dll into the game folder and was able to start the Oblivion.