no start why?

[fart eater]

when i turn the key in my car it makes no sound

[andy hughes]

Your solenoid may be shot - you'll have to get a mechanic in to diagnose and treat.

[Rossyboy]

Do the electrics come on? If so it may be an immobiliser problem...

[Mattk]

or a dead battery/alternator

[Headtime]

Could also be the starter motor.

[Kev_UK]

As already mentioned, solenoid, starter motor (or if no lights on dashboard, a flat battery). You can try jumpleads from another car battery, bump starting, or with the engine off, put the car in gear and rock the car back and forward, then put in neutral and try the key. Another method (often works) hit the starter motor with a hammer (not too hard) then try again.

[Kev_UK]

Oh, another reason could be a blown fuse or faulty earth lead

[chrissmiff]

If its an automatic, check you're in park or neutral

[chrislangham]

check that power is there,is battery flat, is key damaged etc etc then check for other problems systematically