Most "repack" launchers are flagged as "Trojan" or "Malware" because they bypass DRM. Your Windows Defender likely deleted it during installation.
Most users searching for a standalone launcher download are facing one of three issues: gta v launcher exe file download repack
If the installation was interrupted, the executable might be 0KB or missing. Most "repack" launchers are flagged as "Trojan" or
Right-click Launcher.exe , go to Properties > Compatibility , and check "Run this program as an administrator." Important Security Warning go to Properties > Compatibility
Even in repacks, the game often looks for the Rockstar Social Club framework. Ensure you have the Social Club Latest Setup installed (found in the _Redist folder of your repack).