To find the potential culprit, you need to consult your owner's manual's fuse box diagram. Look for fuses related to the instrument cluster, gauge cluster, speed sensor, or possibly the PCM (Powertrain Control Module). A malfunctioning speed sensor often presents as a non-working speedometer, and its circuit may have a related fuse.
Important Note: Before attempting any fuse checks, turn off the ignition. Improper handling of fuses can damage your vehicle's electrical system. If you're not comfortable working with your vehicle's electrical system, it's best to take it to a qualified mechanic.