Can someone plz help me???

Im Bronze 1 and i am constantly playing against people in silver 5-4 and sometimes even gold players. I have only had 1 person play on my team that has been silver. I already have 0LP (just came out of placements) went up to 33 then down to 15 and now i have 0LP I constantly have someone on my team either trolling, afking or I start lagging. can someone tell me how i can win games even if were a player down? Much appreciated