My kitchen breaker tripped last night, and it will not reset?
I have never had to replace a breaker unit before? I thought you just flipped it from off to on again, and it would reset, however at this time it will not reset the breaker. Can someone help with this? I mean the obvious is to replace the breaker switch?

First, and always, shut off the Main Breaker. If the Main Breaker is in the panel you will open, the large wires connected to the breaker are still hot, and can only be shut off by removing the utility meter.

If you Main Breaker is out at the meter, then there should be no live power in the panel

You also need a voltage tester, to test any live parts to be sure the power is off. Breakers can fail and not shut off. Do not assume power is off.

Once you remove the cover of the panel, use the voltage tester one lead to live parts and one to the neutral bar, where you will find all white wires.

Once you are sure there is no power, unplug the breaker, it will be plugged onto a bar or tab in the center of the panel, you may need to pry it gently with a screw driver. The breaker will be seated on the opposite side of the plug on point by a clip or foot, and will come out center first then the foot.

Reverse the process, and connect the wire to the terminal. Be sure the wire is tight in the terminal.

You can find some videos at You Tube and etc to show you the process, however, most DO NOT tell you to shot off the Main, or tell you to use a tester to be sure power is Off.!

Casey...
Did you push the handle "fully" toward the off position and then
Try to turn it on? If this doesn't work and the handle feels loose then
The breaker is likely bad and you can consider TK's advice above...

It may not reset because you may still have a short somewhere.