How to substitue variables in my function/forumals?

Hello,

I wrote a forumula

" IF(D5=$C$5,$A$5,IF(D5=$C$6,$A$6,IF(D5=$C$7,$A$7,"FAIL"))) "


Actually..the one i wrote goes up to $A$67 but i cut it short here for simplicity's sake

Is there a function that will replace every "D5" with something else????? i could not get substitute or replace function to work. I am an excel noob...if and and functions are the extent of my abilities.

thanks,