It suddenly stopped both agitating and spinning and instead, makes this low humming noise. What could be the problem? Is this something someone with absolutely no experience could fix?

Thank you for any/all help you are able to provide me. I have 7 children and this is a major inconvenience for me.

Sounds like it could be the motor. They make a slow hum noise when the are locked up and will not spin. Call for professional service.