After i replaced the valve cover gaskets my car is missing and throwing codes.

Hello, nothing needs reset, something needs repaired. A guess is that when you removed the coils, the rubber insulators could have become damaged on them, resulting in the spark arcing at the plugs. This would cause a misfire. You may need to repair or replace the coils. The rubber dry rots and cracks when disturbed after all these years. Hands on inspection and testing is needed.