Midi drum tracks

I xperimented with a drum track today and had things working great. I came back later in the afternoon and made another one but this time I'm not getting any sound. Any advice?

We're gonna need a little more info than that. It's kinda like saying "my car won't start, how do I fix it?"

what are you using as midi input? a midi controller or are you entering them manually? are you using softsynths? how do you have your sound card set up? wht kind of sound card? as much info as you can give us on what you're set up is and exactly what you're trying to do will help.