My guess and my hope are that it is something minor and by the time you read this you have been on your way and returned. Since the battery is relatively new - I'd get that charger crancking and check for loose connections that may have occurred during the bat. change. Be sure that you didn't bump the kill switch. Think of any cause that may have led to bat. drain - hot wired accessory left on, ingnition left on - stuff like that. If not any of the simple stuff - Check charging system, test battery, ect. Maybe even jump start it one time and see what happens. Then scream, cry, & swear...
Good luck