Why has both top elements stop working at the same time

Check the element with a Digital Multimeter set for continuity (Ohms). If no continuity, the element has failed.

https://www.google.com/search?q=oster+tssttvmndg+element+replacement

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check breaker or power feed my not be getting correct power to the unit may only be getting 110v which electronic circuits work on instead of the 22ov that the elements and coils work on

time for a new element

The grill element should not 'blow' by just touching it - it should be earthed. The elements do gradually disintegrate over time & the inside wire element either fractures or touches the element casing causing the mains to trip. Sometimes this makes it trip just once & then stops working. Replace the element - not usually any fuse in circuit with this. Often held in by 2 screws adjacent to the element at back of oven and conections via Fast-ons- Rick

It sounds like an electronic clock/timer problem. The clock must be in the manual mode for the oven to work. It sounds like it might be in auto. mode for both elements to stop working at the same time.

It is a bit suspicious if both stopped working at the same time. It has to be a common fault. The first thing I would check is the wiring at both elements. You will have to pull the back of the range off to check this. If okay I would suspect the controller which controls both these elements is faulty. Another solution maybe the oven thermal overload but it isn't that common.

Sounds like you need an bake element ignitor if the bake doesn't work but if the broil also doesn't work, it could be the electronic clock/timer control. the part number for the bake ignitor is 8054129 .Best off to call a reliable service company such as Sears.

I suspect a heating element in the oven has burned out. Some ovens have 2 heating elements, one on the bottom for baking and one on the top for broiling. If this is the case, you can try setting the oven on broil and see if the top element gets hot. Usually the bottom element fails first because food gets dripped on it. In most cases you can unplug the old heating element by just pulling on it and plug the new one just as easily. You can check the resistance of the heating element with an ohm meter. If it's burned out the resistance will be very high, probably greater than a mega ohm. In some cases you will need to take the back off the oven to replace the heating element. Just make sure the oven is unplugged and cool when you start working on it.

gerrie824 look at the elements and see if there is cracks in them. If so then yes they failed. During bake the broil elements come on in 1/2 power to brown the top of what you are baking. If there isn't a break in the elements, then the issue could be a burnt wire, failed relay, or such.