2003 Nissan Maxima engine won't do anything

Earlier before I had my problem I was driving and the service engine soon light came on. Now for the problem, when I tried to start my car nothing happened. The starter didn't click or try to engage so I thought the battery was dead but that wasn't the case. When I try to turn on my headlights one of the relay switches called fog lamps clicks so I replaced it and that didn't help (it still clicks). Now when I try to start the engine a replay called engine control clicks. I have not changed it yet. Some other things my car is doing; when you press the brake the interior lights go out and the brake lights come on, when I put the key in accessory position the accessories only work sometimes, my headlights won't come on. Etc. Could all of this be happening because of the engine control relay? Any ideas of whats going on?
Also I cannot get my key out of the key slot where you start the engine. My car will not let go of the key.