How do I get back on my game?

So basically I used to be a OK player, on one of my accounts I got to plat 3 (I know i'm not great but OK) I just came back after a long break, and i'm AWFUL. I'm leveling an account (currently lvl 23) and I never feed, but i'm not at all popping off on level 23's. Ill get scores like 6/6/11 or like 3/2/8, pretty mediocre scores but not standing out at all. The champs i'm currently playing are lux if im mid or supp and vayne adc. Maybe i'm off meta, or i'm just missing something. Any tips? Any input is appreciated :)