My gas oven will not heat up, stove top turns on,

First you will need to verify if the hot surface igniter is coming on when the oven thermostat is in demand. When the thermostat is turned on for the oven you should see the igniter start to glow. You may need to remove the bottom oven panel to be able to see it in action. If it starts to glow then take a wrench and tap the gas control valve located at the back of the oven in the broiler/storage compartment on the bottom of the range. If you tap the valve and the burner comes on then shut off the oven completely and back on several times and make sure it is working. If it does you may have solved the problem. If the burner does not come back on and you have to tap it again then the gas valve is sticking either due to a bad valve or weak igniter. If the igniter does not glow then the igniter could be bad. You would need to verify the igniter is getting voltage. Then the igniter can be tested with a ohm meter. A good reading usually is between 500 to 700 ohms. The hot surface igniter cang get a crack in it causing it to stop working.