Hey (new to this forum)

I've installed it missing out the direct x install which is obviously the problem, but I already have direct x 10 on my PC and im not sure whether installing the old direct x would help or mess my machine up for other games

what should i do?

You can install directX 9.0c. It will not overwrite your DX10 install, just install the missing files.

Other games requiring DirectX should be unaffected.