They make locator's, yes. But honestly, you can easily have an electrician out and install a new line for much less than the cost of one.
Locater of that type is $500-$700 for in wall tracing.
Being only 20 ft from the panel, I would not suspect any junctions on the circuit unless the home is older and has been through some remodeling at some point.
The cable probably runs through the attic and then down the wall to the receptacle.
I would turn off the breaker and visually inspect the individual black wire at the panel and the switch box.
I have seen many times wires being stripped at the termination point and then made up, only to break the wire inside the insulation
So, power cannot pass any longer even though it appears to be intact.
Check all terminations and actually undo and re strip the wires and then reconnect them.
Check where the cables enter the box and panel also, sometimes they are broken at the entry points but not near as often as at the connection points.
Verify that there are no other receptacles on that breaker by turning it off and test all in the area.
There could be one on the circuit and only be a loose connection in the receptacle which is the #1 most common problem.Fluke Makes an in wall tracer #2042 for your reference.