Can't pass 1300 elo for 8 month...
@1
"I had played close to 2500 games"
++ Stop playing blitz & bullet, play 15|10 rapid if you seek progress.
"I seem to have forgotten everything about chess" ++ Blunder check before each move.
"Sometimes I can make good moves"
++ You do not win by good moves, you lose by bad moves.
"what to do at the beginning of the game"
++ Develop your pieces into play towards the center.
"at the end" ++ Learn basic endgames.
"I just play aimlessly" ++ That is bad. Always play your piece that stands worst.