What does the computer reset button look like on a 1992 Ford Ranger?

There is no "computer reset button" on a 1992 Ford Ranger (or virtually any car from that era). The engine control module (ECM), which is the "computer," doesn't have a user-accessible reset button. Issues with the ECM usually require professional diagnostics and repair. Some problems might be resolved by disconnecting the battery for a period of time (to clear any stored codes), but that's not a button press.