Repair a Viking range that does not heat by first checking the power and gas supply, cleaning the pilot light orifice and turning the oven off to reset the unit. If these repairs do not work, call a professional.
First, make sure that the range has a power supply. It should be plugged into a live outlet. Check the outlet to see if it's faulty. Make sure that the circuit breaker hasn't been tripped either. If the power is working, make sure that the gas valve is opened all the way and the gas lines are not kinked or blocked. If the range still doesn't heat up, turn off the power for 30 minutes to reset the unit. Turn it back on and check to see if the oven heats up.
Another possible problem is a dirty pilot light orifice that can interfere with it lighting. I can get clogged with food debris or grease. If you need to clean it out, first disconnect the range from the power supply and shut off the gas. Open the oven door and remove all the racks. Clean the orifice out with a straight pin and rag. If the range still doesn't heat, contact Viking for help and call a professional.