Did it run rough prior to parking or always been perfect?
Could be a few things i'm sorry to say so quite hard to diagnose, we had a similar issue and it was the coil pack eventually, after changing, spark plug leads and spark plugs!
Sorry that is such a vague response, but there are a lot of variables that need checking, does it have a spark? is it getting fuel? will it start and keep running with foot on accelerator?