My 1999 camry 111,000 miles 4 door does not allow gear change and the car to start.

This occured when I absent mindely tried to start the car though the car was on. When the brake got stuck in trying to resolve it I pressed the remote keyless entry which then triggered off the antitheft alarm . Someone that came to help me pressd the antitheft alarm light flashing a couple of times

Urgent help needed