Retrieve my old world back

[TSM]

I recently came back to my old server to play again with some friends of mine, and when I tried logging in again after being afk for about 5months, it just kept sending me back to the minehut lobby. Every time I log into the minehut lobby, it tells me I am using an older version (1.15.2) and so, I switched to the new version and it finally allows me to join my own specific server but it is a completely new world. Any reason why my old world does not load?