Please provide some additional information and clarify a couple of things.
Is the lift pump on a circuit by it self?
Please describe what you did in changing out the light fixture. Changing out a light fixture can be as simple as disconnecting the fixture wires from a single house cable in the fixture box or it can mean disconnecting several wire splices in the box. In other words, describe the wiring in the box and what you had to do to change out the light.
I accidentally shut the one off for the lift pump. I immediately turned it back on,
Does that mean you inadvertently turned it off and then back on? Or does it mean you turned it off, later discovered was off and turned it back on. When you turned it back on did the lift pump start? If so, was the washer used during the period the breaker was off?
Your association between replacing the light fixture and the failing lift pump may or may not be valid logic.
When this happened I immediately turn to the breaker box and find that it has not thrown the breaker and should still be functioning... However I reset the breaker and the lift pump begins to operate sucking the extra water from the washer back where it should
Many, if not most, circuit breaker do not move to the true off position when tripped. Common advise is to feel the handle to determined if a breaker has tripped. Pushing it toward the on position. If it feels solid it has not tripped. If it feels spongy it has tripped. It is also common advise to say turn the breaker off then back on, to be certain it has not tripped.
It certainly sounds like your lift pump failing because the breaker is tripping. The question now is what is causing it to trip. It also sounds like you can not determine if the breaker has tripped by looking at it, you need to feel it.
So I guess I'm saying that your association between changing the light fixture and the failing lift pump may not be correct because the breaker may have been tripped previously, that you did not inadvertently turn off, only discovered that it was off and reset it.
You association between replacing the light fixture and the lift pump may be valid however. It is possible that even if the lift pump is on a circuit by itself, if wiring goes through the light fixture, you could have made some error in disconnecting and reconnecting the wiring that is now causing the breaker to trip.
Circuit breakers do wear out and can fail, but that is rare. In many years of home repair jobs I have only found one faulty circuit breaker. One way to test for not only a faulty breaker, but also a fault in the entire lift pump circuit is to get a heavy duty extension cord and plug the lift pump into another circuit.
Your assumption that since the lift pump is only 3 years old it would not be faulty, may or may not be correct. Plugging the pump into another circuit would help confirm or eliminate that possibility.
So, please describe in detail the wiring in the light fixture box and what you did. Confirm that the only thing on the lift pump circuit is the pump. Let us know whether not the washer was used during the time the breaker was off and whether the pump came on when the breaker was turned back on.