Hi,
I have a 99 accord LX, for last two days I have noticed that the car shuts off while driving, and then when I change the gear to parking mode and crank the ignition key again, it starts running, can somebody tell me wats wrong?

I would begin by testing/replacing the main relay, igniter, and coil. AutoZone will test igniters and coils for free. Be sure and run the K-Test on the ECM.

There's an outside chance it may be related to the automatic transmission interlock system:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-46563-3.html#post258005