It sounds like you may have a power issue going to the oven. The first thing to do in trouble shooting the problem is reset the breaker to the oven. It is possible that half the breaker is kicked. This is the reason the 120 clock works and the 240 volt elements don't. Reset the breaker and wait five minutes then turn the oven back on.
See if this helps. If not then next thing to do is inspect the wiring to the oven. Look for burnt wire ends or faulty connections. It is not likely that both the elements have failed at the same time. The issue sounds like a power problem to the oven.
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