My car wont start the battery is fine dont know what the problem is please help

IF the car cranks over but doesn't start you need to see if you have Spark and Fuel. IF it doesn't crank, check starter and related circuit, tapping on starter will sometimes help to get it rotating. Check all fuses, and make sure battery terminals are clean and tight. Have someone or yourself connect a scanner DTC reader and see if you have any engine computer faults. If manual transmission make sure your clutch pedal switch is not missing the bushing. Aftermarket alarms can cause no starts also, but usually a "no-crank" situation.