2000 Peugeot 206 car won't start, doesn't turn over.

Try moving gear selector .If not that may be flat battery .Either try a jump start or charge / replace battery

Could also be the inhibitor switch which prevents the starter motor from being operated unless the transmission is in the P or N position.

Also check power to starter motor ,it may be a faulty starter,and check your earth lead from the battery to chassis or gearbox is intact.