99 jetta has power but doesnt start
 

my 99 jetta has power but will not start and my alarm system seems to have shut down and it mightve locked the engine is there anyone who can give me advice on what to do or how to fix this problem. i had the car running and nnoticed that my windows would not go down so i turned car off and tryed to restart it but only the power came on nothing else.. any info is great info thank you!!:)