Some preferences may not survive every interruption or reset. Missing favourites do not automatically mean that the cooking elements have failed.
What the observation means
Check whether only personal programmes changed or the clock, units, language and other settings changed too. That distinction helps identify a preference reset versus a wider power problem. Restore settings using the normal owner menu rather than guessing the former temperature from memory.
A useful next step
If resets recur during ordinary use, record their timing and whether other appliances were affected. Repeated circuit trips or electrical warning signs need assessment. Do not keep reprogramming the oven as a workaround for an unexplained loss of power.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.