Has new starter and battery. Trying to start its dead though when battery connected to charger starter hums. Weird!

I have moved your post here from the forum help area. The forum help area is where you ask questions on how to use this site.

I know it can be confusing.

Someone will be here shortly to help you with the lawn mower isusue

Hi,
With just the info given I would say you have a solenoid stuck "closed." Do need more info like brand, model, engine, model, type, etc.
Peace,
Clarke

Also,make sure battery is fully charged. When it hums try lightly tapping on the starter,and see if it will turn over.