Having a hard time winning games lately.

So, for the last little while, I've been having a hard time climbing the ladder. I'll loose and take a break to relax so I don't tilt. But lately, I've only been loosing and I can not seem to figure out why. I want to blame my teammates, but I know its something I'm doing wrong. Every game, I get a massive lead during laning phase. I get to the point where I can 2 v 1 no problem. Come mid game, everything goes south. My team and I can't get objectives and we end up throwing the game. My games are starting to average 45 to 60 minutes now. I try and lead my team to victory, but they never listen. For example, I'll say "we need to focus objectives, lets take mid tower." No one listens and they go do their own thing and get caught out. Basicly, My laning phase is good. I need advice on closing games out and how to get my team to work together. I would also like advice when the other lanes loose hard what to do then. That doesn't happen every game, but it happens often. Like 1 out of every 3 games for me. Any advice would be great. Thank you!