I Am Stumped

So i was doing very good on a roll with only playing fiora top(rework). Almost got to silver. In fact i was one win away from it, when i started going insanely down hill cant win anymore. Now i main yi.

Now i know im not a very good player by far and i would love help to improve. On the other side i feel like i just cant do anything when i am doing good its very demoralizing. When im doing ok most of the time mid/bot is too fed for me too help. When im losing lane(happens a lot) usually no one is doing good.

Thanks for reading would love help

Failed promos to silver 9 times now rghh