Game install problem

[MAL1]

I need help with a game install problem. I tried to install spearhead and the install failed, stupid computer froze. Then when I try to install it now it wont let me it gives me that repair or remove screen, it wont let me repair or remove the game as there are files missing?? So I have removed every thing I can find that is spearhead of my PC but I still get the same screen repair or remove. Anyone know what I am missing so I can install the game?