If you own an original DVD copy, you have a legal right to the game files. However, the disc contains an older .exe that relies on obsolete DRM (SecuROM) and GFWL. You can legally apply official patches from Rockstar’s website—though those are now harder to find. Most users with a DVD copy are better off redeeming the product key on Rockstar’s launcher.
: If your file is missing or corrupted, right-click the game in your Steam Library right arrow Properties right arrow Installed Files right arrow Verify integrity of game files gta+iv+exe+file+download+hot
sfc /scannow