Will not turn over, only headlights turn on, no electrical

My car has been sitting for about a month, as I was away on work. I made it home to find it will not start. I had the dash lights turn on once. I replaced the battery and no change. Thought it might be the starter. I have a new one just in case, but have not replaced it yet. Fuses look good still. I cannot find the in line fuse. There is no turnover, no clicking, and no life at all except I can turn on my headlights. I have tried to reset the ECU, but may have done it goofy. I read it was found under the drivers seat for this year and model. I just unplugged the cable for fifteen minutes and re-plug it in. Any advice or tips that may help are very much appreciated!