* For the radio/electronics: There's usually a small fuse that controls the radio. Check your owner's manual for the fuse box location and diagram. Removing and reinstalling this fuse might reset the radio. A completely dead battery might also require a radio code to be reentered.
* For the computer (PCM): There's no easily accessible reset button for the Powertrain Control Module (PCM). Disconnecting the negative battery terminal for a few minutes is sometimes suggested to clear temporary issues, but this isn't a true "reset" in the sense of reprogramming. It's more of a power cycle. Caution: This will erase any personalized settings like radio presets.
* For other electrical issues: If you're having specific electrical problems, the issue isn't solved by a simple switch. You might need to diagnose the problem (blown fuse, faulty sensor, etc.).
In short: There's no single "reset switch." The best approach depends on what you're trying to reset. Consult your owner's manual for more detailed information, or seek professional help from a mechanic if you're experiencing persistent problems.