Learn how to lose without being 0/15 before you go into ranked
Losing a lane should put you back a few deaths, barring extreme circumstances. If early game ends and you are some awful 2/8/1 you need to sit back and ask yourself, "was that, at all preventable on my part?". If you said yes, work on losing your lane without going balls deep in feed. find someone better than you and practice fighting someone with more gold, or cs.
losing is part of the game, and it will happen. you just have to find ways to lessen the pain, and still provide man #5 for the team