well recently I have bought the game fahrenheit and every time i try to download part 1 it says this message : The setup files are corrupted. Please download a new copy of the program.
Please help! I will do anything!

You will have to download all parts before installing.

Are you using the downloader?

When you go to "My Games" and select the game, you will see a list of installer files to download on the left side, something like

Windows installer (part 1 of 3) 1 MB 2.0.0
Windows installer (part 2 of 3) 2 GB 2.0.0
Windows installer (part 3 of 3) 180 MB 2.0.0

Part 1 is an .exe file, parts 2 and 3 are .bin files. The .exe will only run if you have the two .bin files in the same folder as the .exe.

(edit)
If you have "GOG.com Downloader mode" on, turn it off to see the direct downloads.

ill try it ;)

Part one doesn't work until all the parts are downloaded though. Part one probably downloaded fine, it just doesn't work on its own.

so when i download part 2 it just says No suitable decoder module:
VLC does not support the audio or video format "undf". Unfortunately there is no way for you to fix this.
i dont think i can fix it. but plz help if i can

Right, you're not supposed to run part 2 (or 3 or 4 or however many there are supposed to be), they just need to be in the folder with the installer so it can access them.
Also you don't need to PM people to let them know you've replied to them. ;)
If you reply to someone's post using the reply button then the forum lets them know someone has replied to them.

yea i sorted it out . all i needed to do was put part 2 and 3 in the same file as part 1. thanks for all your help :D (thank you :3)