I went to start my 94 Altima last night and it would not start. Then I noticed that the little alarm light which has always been green is now blinking red and all the lights are flashing. It looks like some how my anti theft system was activated and has locked me out of starting the engine. The car doesn't have keyless entry so I don't know how to make it stop. Please help. I don't know anything about cars but I am hoping it's a simple problem that won't require me bringing it somewhere and paying money to fix.

it's probabbly to late to answer. If it is an aftermarket alarm , most cases you can unplug the alarm control unit ( the black box with all the wires going to it) and you can start you car up with no problems