engine turns but does not start?

Hello , I have a mercedes benz c220 1996. The battery was disconnected for a long while. I had to repair a broken exhaust camshaft. After all is done, the engine turns but does not start. There is fuel in the ramp but no spark. All lead to the infrared key not in sync. Can you please detail me the procedures to resync my key.
THank you very much.