Peugeot speedfight not starting again? ?

i was riding home the other day around 25mph (coming upto a junction) and my peugeot speedfight just cut out? and wont start again? ive got fuel, new spark plug, new battery, oil and compression and its still not firing? i dont have a clue what it can be but ive always replaced the immobiliser unit a few months back so i dont think it could be that? please write back please.