Transmission went on neon- now won't start at all

Hi. the transmission went on my 99 plymouth neon, but it was still running in 1st. I let it sit for about a month while I shopped for a new car. Now i went to start it to move it, and it won't start at all. I just replaced the battery a couple months ago. But the headlights won't even turn on. Would the tranny going cause this? Anyone have any ideas? Thanks so so much!