focus wont start

I have a Ford Focus 2002 and the anti theft light won't go off and the car wont; start. I only got one key so i can't reprogam the key meselfs.everyone tells me to go to the dealer..i on the owner manual,,they say.,.if you put the switch in the number 3 postion,,.the anti theft light must go off in 3 sec,,mine does,,but when starting the car,,,i't wont crank and the light keeps flashing,

please help

Thanks for your time,