Items gone in multiplayer world, "Player data" problem?

Hello, I had to download and upload an Advent of Ascension 2.4B world into my aternos server because I didn't know how to resolve a past issue, all of my items and skills are gone and so are on my brother's account. Items and Skills are saved in level.dat under players... but I don't understand anything there, every "player section" (there are three, I think we entered on a third account as well, can't remember) has all same values. Is there a way to restore everything?