It's a 1999 and one day I had to come to a abrupt stop and when I did the vehicle shut off and ever sense then the brakes only work barely when the pedal is pushed to the floor. The brake fluid level never changed so I don't know what is wrong.

 

All your lines look good? I assume you have rear drums? Have you opened them up to take a peek? Usually in my experience, pedal to the floor means air in the line and you need to bleed them- other than that something is broken.. If something is broken, you should be able to ID it fairly easily. Just have someone pump the brakes while you are under it... Watching for leaks. If no leaks,Start with the simple things like adjusting them etc. Sounds like you blew a cylinder to me.