This could be caused by wet ignition electrodes that might be shorting the spark preventing it from sparking the gas. Try to dry your burner with a hair dryer  around the  ignition electrode and try again. If the issue continues, you might need to inspect some other components, such as spark module or spark ignition control board, wiring harness, ignition electrode, ignition switches, faulty burners, etc. based on the brand and model of your stove or range. A professional diagnosis ensures the correct repair, saves you time, money and hassle of repairing that might cause additional damage to the unit if repair is not taken properly.

The very first step you could try is to turn off the oven or your range or stove for 2-5 minutes by unplugging from the outlet or switching off your circuit breaker. It will reset all electronic control boards used in your appliance. Then remove everything from your oven, make sure that the door closes properly. If within 10 minutes it doesn’t reach 350 degrees then deeper inspection has to be done in order to find causes of that issue. Temperature inconsistencies may result from a faulty thermostat, heating element, temperature sensors, selector switches, control boards, wiring harness, safety thermal fuses, door switches, etc. Accurate diagnosis and replacement of a right part guarantees  proper operation and restores accurate cooking temperatures.

Microwaves have multiple parts involved in the heating process. Failure of any of the parts will cause heating issues you might have. Common causes include a defective magnetron, high voltage transformer, high voltage, main or noise filter control boards, blown fuses or thermal cut-outs, faulty high voltage capacitor, high voltage diodes, faulty door switches,  etc. Caution with microwave repairs has to be taken seriously as high voltage capacitors retain a charge that even after unplugging from the outlet might cause a life danger if shocked. A certified technician can safely diagnose and repair the problem.

Buzzing or humming sounds can indicate electrical or mechanical issues, including malfunctioning control board relays, failing cooling or heating fan motors, door lock motors, faulty magnetrons in the microwaves, vibration from different components inside the stove, range, oven or microwave.
Clicking noises from stove or range burners are very likely caused by  wet ignition electrodes due to spills or a wet cleaning. Due to the age of the appliance they often get cracks that cause them to malfunction later. Another reason might be one of your stove or range faulty ignition switches. 

After scheduling an appointment, the technician will arrive at the set date and time to diagnose the issue and determine what parts are failing that need to be replaced, scope of work required to replace them. If parts are available, the technician will give an estimate on the spot and will try to fix your appliance right on the spot. In this case he will seek your approval of the estimate right at that time. If you as a homeowner or appliance owner are not available to make such approval for some reason he will be leaving without a repair. Another trip charge will be applied to the repair next time if you decide to follow up on the repair later. If parts are not available, a written estimate usually sent by sms text message will be given to you next business day, detailing what parts, their price, shipping costs and labor required to complete the repair. Most of the ordered parts will be shipped with ground 3-5 day UPS, FedEx, USPS carriers (or overnight if needed faster) and will be installed on the next business day. The technician will keep all communication with you once the part is delivered to schedule a repair appointment.