santa brought bachmann train set last year. dad did not register it. :'( is not working what should i do
Is it working at all? Are other trains working just fine on the same track?
The first thing to do is to look at the wheels and see if they are dirty.
One other area to check is to make sure you have the connections to the track correct.
If you have a second HO engine or if a friend has one, try it on your track to see if your issue is the power supply or the engine itself. If the second engine doesn't work, then you know that the issue is your power supply...which probably means the connections between the power pack and the track aren't correct (it could also be the power pack, which is far less likely). If second engine does work, then the issue is your engine.
Also most hobby shops will take a peek at your locos for you for free