* If you mean resetting the trip odometer: This is usually done by pressing and holding a button on the instrument cluster (speedometer). Consult your owner's manual for the exact procedure.
* If you mean resetting a specific electronic system (like the radio, or a malfunctioning component): Each system might have its own reset procedure (e.g., disconnecting the battery for a short time, or following a sequence of button presses). Again, your owner's manual will be your best guide here.
* If your car is experiencing a more serious electrical problem: Simply disconnecting the negative (-) battery terminal for a few minutes might help. Reconnect it and see if the issue resolves. However, this won't fix underlying mechanical or software problems.
In short, there isn't a central "reset" switch. You need to be more specific about what you're trying to reset.