Try out his Microsoft support answer:
https://answers.microsoft.com/en-us/...ae764c1?auth=1
First they advise to download the web-installer which will install missing files for DirectX (Win7/8/8.1/10 should have all DX - 9,10... 11). If one of the files is corrupted and the first solution does not work you can try the second download of the DirectX Redist (June 2010) which will then also override and possibly fix corrupted installations.
Btw.: due to the error message claiming "Could not enumerate Directinput devices...", did you by any chance also install/change a new keyboard, mouse or headset that may not yet correctly be recognized by Windows DirectX, or unplugged anyone of those ?
Last but not least from the LotRO forum, try the suggestion of fallohide to detect issues with the dxdiag tool:
https://support.microsoft.com/en-gb/...-run-dxdiagexe