direct x 8.1 error on windows 7

I run windows 7 64-bit professional, directx was working previously but a few months ago my system did a standard windows update. after this a game stated it could not start due to directx 8.1 error. In un-installing and re-installing the game it filled up all of my restore points (thought game issue rather than system), so cannot do a system restore anymore.

I tried re-installing directx 8.1 off an old game and then said a newer version was already installed and so did nothing.

I have tried installing past DirectX End-User Runtimes and the directx web installer. these all either say a newer version is installed and do nothing, or install files but that does not fix the problem.

I have the original install disc for windows 7, but cannot find an option that repairs without offering to do a full re-install of the operating system.

I have checked that I have the correct files in system32 directory, DXDIAG displays version 11 present and reports no issues.

/sfc scannow has reported some errors but cannot fix them.

Please help!