Land Rover Discovery 2 won't start

Hi am wondering if someone could please help as I have conked out, basically it won't start & the green M & S light are flashing on the dash,this has happened only twice in 2 years but after switching engine off & running the auto gear lever up & down through the gears it has rectified itself quite quickly,not this time I have checked battery connections / leads etc they seem to be fine,I must admit that this might be my own fault a little because I tried to star up in Drive when I noticed I whacked it into park quite quickly & they started flashing straight away ( not really sure though if this has anything to do with the problem,also I managed to have a look underneath the cover around the gear stick & their is a small black sensor attached to to wires which definitely looks like it should slot into somewhere but searched for 2 hrs & can't see anywhere where this thing goes.Disco had a new auto box fitted a while back so just wondering if this small sensor block is just not needed anymore ?? anyone have any ideas if I can do anything at all to get it started at least to get me home ?? Thanks in advance regards David.

It could be the XYZ switch,that can give problems like that,especially since you found the item by the gear stick area.Also post this in the Discovery section,get more help in there,good luck.

Hi just reposted in other section....cant believe i have had a look underneath & found no drainage plug at all on bottom of gearbox.....just a deep threaded hole about size of 20p piece.....im assuming this has to be the problem.....cheers david...