Changing Key Codes?

[Arcangl123]

Does anyone know how to change Key codes on Battlefield 1942 while it is installed? I lost my key code and now I am using a Key generator but none of these codes seem to not let me in the multiplayer so far. I have been installing and reinstalling the game over and over again to be able to put in the new codes. If anyone knows a quicker way I would be very much obliged.

Thanks in advance

[JoyBoy]

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