Hello!
The game hasn’t been updated since 2017, so there’s no reason why the trainer should suddenly stop working. 
If you have a cracked or pirated copy of the game, which will often experience that issue you’re having, then this is the cause of your problem. Trainers are not and never will be made to deliberately work with illegal copies of games. The game is 75% off on Steam right now for the next 22 hours (£3.49 GBP).
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If you have the game from Epic Games, you need to use the Epic Games trainer: BioShock 2 Remastered Cheats and Trainer for Epic Games.
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If you do not have the Remastered version of the game, you need to use the trainer for the standard edition: BioShock 2 Cheats and Trainer for Steam.
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If you have the game from GOG, there currently is not a GOG trainer for this game.