Assuming you're not deaf, you have a starting problem that may be due to a dead battery, a loose or corroded battery cable, a bad ignition switch, an open neutral safety switch, or a bad solenoid or starter.
Total silence usually means no juice is getting through to the starter. So start with the battery. Is is dead or does it still have a full charge? Are the battery cables loose, corroded or damaged? Be sure to check both ends of the cables, including the starter and ground connections.
If you don't find any obvious problems with the battery or its connections, voltage may not be passing through the ignition switch circuit to the starter solenoid. A voltmeter or 12 volt test light can help you see if voltage is reaching the solenoid when you turn the key.
If voltage isn't getting through, try jiggling the gear shift lever. Some vehicles may also have a safety switch on the clutch pedal that prevents the engine from starting unless the clutch pedal is depressed. Use your voltmeter or test light to isolate the component that needs to be replaced or adjusted. Sometimes the transmission or clutch linkage may need to be adjusted for the safety switch to work properly.
If voltage is getting through the ignition switch circuit, but the starter isn't doing anything, check the wiring connections on the solenoid and starter. Are they clean and tight? Try bypassing the solenoid. Refer to a shop manual for the proper terminals, then jump the one that routes voltage directly to the starter (usually B+ or BAT). If the starter spins, the problem is a bad solenoid (or poorly grounded solenoid). If nothing happens, the problem is a bad starter that needs to be replaced.