If you own the game legally and lost the installer, you can:
Steam is the world’s largest digital PC game store. When you buy GTA 5 on Steam, you download steam.exe (the client). Steam then handles the verified download of GTA 5.
The screen flickered. A black box opened—a command prompt, old-school and sinister. White text crawled across it like a confession: “Extracting bootstrap… Bypassing integrity check… Patching hosts file…” For a sickening second, he saw the word WRITE: SYSTEM32 . His finger twitched toward the power button. But then the window vanished.