when i tried to pathc far cry it didn't work and an error message tells me that i have to install the game before i patch it although it's already installed

ps: i wanted to patch the game because my old 17 inch crt hitachi goes to suspend mode right after the load screen finishes and the monitor tells me that the input signal is out of range , i know i have to update to the latest monitor drivers but this monitor is discontinued ,, so how can i fix this problem ???

please help