League points

I want to know how the league points are awarded, I want to know this because i used to lose about 16-18 LP and gain 22-28 for a loss and win in bronze, but these days in silver V i lose 24 LP and gain 10!!!! [I remember a couple of months back i was still getting decent LP and the loss LP was always less than win LP] I have been in SV for a few months now and I wondered why I never made it to promos even after playin for so long! and now i look at the LP win/loss and i dont understand what is happening and the teams are never dependable in in soloQ, i have a win rate of 50%! and this way i will never progress in ranked no matter what my individual skill level is, there is always someone trying a new champion and no one really blames them but its hard to win 3 game for every game i lose! so this way I will never progress!! I am just wasting my time playing! now riot really cant expect a player to continue when he has no chance of progress even at 50=55% win rate. can someone please explain what happened here?