initial timing help

i went to go change my dist gear but while i was doing it the gear got stuck so i tried tunring the motor by hand a bit to get it out now im goin to put stuff back together and i realeased all the marks i made b4 are useless for getting close to teh timeing. so my question is how do i get the timing back to where it has to be im guessing its get to to top center but i dnt kno wat else all the help is really appreciated