tips for climbing? and how do i improve my mmr quickly

Long story short, im seeking advice on how to climb quickly but also improve, tbh i think im a decent player, im only silver 1 but i was gold 4, then i sold my pc and didnt play for a month, and when i got it back i deranked from being stubborn and playing ranked, now im gaining 13 and losing 25 when im actually back to performing well, do anyone have any advice, because if i hold a 50% winrate from here on out i just get deranked due to mmr, also do anyone have some really good advice for how to climb, i can openly admit my biggest issue is not sticking with a role, twice i made it to gold once on support once on adc, im a really good support i would say i play this role at plat, had a 70% wr on thresh and 80% on morg and good wr on others when i hit gold this season, but i got bored and played other roles, i admit im not good enough to reach my goal right now, but thats why im asking for advice, i have good mechanics and understand the game very well imo, i know all champs i know how to call, decent laner and average cs, but its something about split second decisions and thought process which holds me back, any advice? open to all criticism & tips