This is due to the fact that the game has recently been updated to version 1.2.0.43 and after reinstalling the game, some files have changed (for example, LaunchGTAIV.exe now PlayGTAIV.exe ) which is why the old version of the trainer no longer works.
For many players who have the Steam version of the game, after reinstalling the game, the old version of the trainer (intended for version 1.0.7.0) could stop working.
