My bmw just died i need a mechanic?

My bmw just died i need a mechanic?
i was driving when all the sudden 2 inches of snow fell and i could not make it home,it is a 1998 323is i was going up the hill when all the sudden a guy passed me and his car couldn't make it up to the hill,his car did slide down to me so hit the gas and i went to the side of the road i hit the gas to take it out od the mud and it just stopped ,what could it be?,when i try to start it it just doesn't
it is cold weather
someone told me to desconnect the battery then conect it again
what can it be? i am confuse because it was running excellent,i check the belts and it is ok
some help
i am asking cuz it is bmw and they are so complicaed
all answere accepted
17 hours ago - 3 days left