How to win games?

So this seems like a stupid question but I want to know how to win. I'm trying hard to carry, and I know a lot of the people say there's always a way to carry, but I really can't get my team to win alone. My last game everyone went negative K/D accept for me. I tried telling them to group and giving suggestions but a few of them started being toxic and we ended up losing. Our comp wasn't the best but I really believe we lost due to feeding early game. If it is possible to carry every game than I don't understand what i'm doing wrong.

I'm not trying to be challenger but not being bronze would be nice. Can someone tell me what I may be doing wrong? I'm trying to get better at more champions to better the team comp and right now I only play normals because I don't want to get into ranked without being good enough and then getting frustrated with the teams I get matched with.

What do you guys do when your team is feeding? Or what do you do when someone on your team is being toxic? Can you recommend any good strategies maybe for when my team is down in kills and losing the match?

(And I know it's funny to type "get gud" in the comments but please don't. I'm looking for some constructive feedback and help here.)