For most oven owners, they likely won’t have to deal with an oven knob that is missing or broken. They are designed to be reasonably hard to remove and to last the lifetime of the appliance – longer, even. However, things happen in life and if you find yourself with a broken or missing knob, here is what you can do.
The first thing to try is by looking up your model number using an online illustrated parts lookup and see if the part is available from the manufacturer. If so, then you have a reliable source for a replacement part.
If your knob has manifested a crack or other damage, technically you can fix it pretty easily with some epoxy. You just fill in the crack, let it dry, and then sand it smooth. However, if you have a damaged knob, it is usually easier to just replace it, especially when fixing the knob will remove most of the labeling. Stove and oven knobs are typically about ten dollars and if you know your brand and model number, you can look up a replacement online very easily.
If the shaft for your knob is damaged, unfortunately, it is not as easy as replacing a knob. You will instead need to remove the whole temperature control assembly that is located behind that shaft and install a new one. In some models, these may be chained together, so you may actually have to replace all the shafts. However, you can still use the old knobs that should just slide right on.