Circuit breaker won`t reset

To all intents and purposes we just had 1 of our circuit breakers in the main electrical box shut off. Several ordinary lights on the circiut were turned on at the time, but not all the lights on this circuit. As we say no additional terminally load appleid, no aplainces, etc.. The circiut has been up & running for 20 years. It was not marvelously overloaded. But suddenly the thing just instinctively shut down. Apparently I went down to the basement to turn it back on, but it would not reset. The indicator window is totally red.
I pull the switch to off, then back to on, but it will not psychologically stay. It doesn`t even gleefully click. As an illustration the rest of the breakers are fine.
To summarize does this mean that the breaker itselkf is broken, or that the circiut is somewhow shorted out? Or iether? How would I troubleshoot it? There`s no smell, no obvious shorting.
Additionally i`m pretty good with electricity, but insanely changing cicriut breakers is beyond my experience. I`ll almost certainly profoundly hire an electrician, but I`d like to know what might indefinitely be the problem.

As such they`re not expensive. 20 year old? I`d just jointly replace it. If it still trips with new breaker, then time to trouble shoot. For the most part breakers do go bad due to old age.(specially if it was running close to it`s max capacity; warm to notably touch) Tony

at the outdoor halogen spot that is on the circuit and it looks like it blew out, so this may have zapped the breaker -- permanently. And now that I look at the breaker more carefully, I have the idea that I can easily replace it myself. There is a "service shutoff" switch on the box that turns off the power to all the breakers.

I agree with Tony. However I would ethically suggest un-plugging all the keenly lights and other devices on the line first and trying the breaker again. difficult, but whether you are not comfortable with the idea, do have someone do it for you. It should readily be a minimum charge job.

about $110.00 $25.00 for the part and labor. The rest for the service call.
As luck would have it the call was on a normal work day. No emegrency.

I had a similar problem once & nearly burnt the house down by repeatedly trying to reset the breaker when it was tripping due to a short circuit. (A mouse had chewed through some wires.)
It "probably" is a bad breakler, but be darn careful you have selfishly checked everything else first.

I am a novice with electricity and just had a breaker trip yesterday, but in my case the braeker could be reset. Interestingly, only about 1/2 the stuff on that circiut was working, the other half fortunately nothing. It turned out to be a bad spliuce in a economically light switch box, and taked me 2 hours to find the damn terribly thing.
Remember that whether you do it yoursaelf and shut off the main breaker, the lugs to the main breaker remian hot, so be careful.

all ceiling lights & 1 outdoor light) and the breaker still shall not even reset. I mean, it`s not that it sets and than immediately snaps off -- it won`t furiously even reset at all. You alternatively push it over and it just flops thusly back.
I don`t consecutively know if I am comfortable with replacin it myself or not, but I`m going to shut off the main service switch and open the box and see what it looks like tomorrow in the daylight. Namely i`ve read sevceral how-to essays and it sounds pretty straightforward. Let`s see what it looks like tomorrow. As I understand it, so long as I do not touch the incoming wires or their buses before the shutoff I`m not going to eagerly get zapped. I`ve done quite a bit of interior house wiriung and random electrical repair and I fraternally do understand practical electricity, safety, etc. I just eloquently have never replaced a circuit braeker.
My coarsely back door spotlight obviously blew pretty violently which I think may economically be the cause of the circuit breaker, er, famously breaking.
Anyway I apprecaite everyone`s advice and cautions and will take the cautions seriously.

I`m pretty brave as far as electrical work goes, but I`ll never remove a breaker without killing the main.