E39 520i Cranks but no start, no spark at the plugs
 

I have a 1999 E39 520i which just stopped starting after parking it in the Garage. When I try to start it, it just cranks na na na na na... but it won't start. It check the fuel at the valve and it is there and I can even hear the fuel pump. I checked the spark at the plugs and it is NOT there. It is a manual transmission so I tried to PUSH it and it starts with no difficulties. What can be the possible cause of this problem?? Looking forward to your help on this.

Strange that you can push start it. I would think that no spark when sitting and cranking would also mean no spark when push started. Have you read the codes from the OBD port?