Try verifying your installation. This will let the Social Club launcher (or Steam, for Steam versions) verify all game files and re-download any that are corrupt or missing.
For the standalone, Rockstar Warehouse version:
Hit "Start", "Run", and type "cmd" without the quotes. Hit enter.
Type "cd c:\Program Files\Rockstar Games\Grand Theft Auto V" without the quotes in the cmd window that pops up. Hit enter.
Note: If you’ve installed the game to a different directory, enter that directory instead.
Type "GTAVLauncher.exe -verify" in this window (no quotes again) and hit enter.
For the Steam version:
Right click the game in the “Library†tab.
Click “Propertiesâ€.
Click the “Local Files†tab.
Click “Verify integrity of game cache…â€
Also
Check your “launcher.log†file located in “My Documents\Rockstar Games\GTA Vâ€. There are helpful errors there that may give more information to assist you in resolving the problem. You can search the Support Site for specific info in that file.