My oven thermostat need to be replaced. The button that turns the oven on is broken. I changed the knobs hoping for a cheap way out and all i got was 2 knobs lol. Can someone let me know how to replace the thermostat. thanks

the knob that turns my oven on must be pushed in so it can turn on the oven. It will not do that anymore. I can spin the knob in circles but it wont turn on the oven. I had someone look at it and he told me the thermostat was bad and wanted 250 dollars to repair. so after kicking him out of my house I bought a thermostat for 40 dollars. what i did yesterday was instead of replacing entire thermostat i took off the knob that turns oven on. I took off the 2 screws and the metal piece that the knob goes on and replaced it. It seemed bent for some reason. But after I replaced it the oven works fine. all knobs working well and oven heats up just like it always did.