[Manuel550]

If this is a bought game, send a message to Rockstar-Games and ask them to fix the issue.
If it is a cracked one, download and install Transmission-QT, go to ******* and search for GTA-SA free download.
I'll recommend you to download one of the last uploaded GTA-SA's in order to make it work fine with SA-MP.

Regards, Manuel de Jong.