Not an electrician but have dealt with this issue over the years. Here’s some items to check:
— check that no rodents chewed wires in the wall or attic on that circuit.
— check outlets and switches on the circuit. They can go bad and more likely than the breaker itself.
— nails driven for hanging pictures can short out wires (don’t ask how I know this).
— overloads: too many items drawing too much current on the circuit.
— a faulty lamp or appliance using the circuit.
— an outdoor outlet that is on the circuit that got water in it.
Good luck.
Thanks!