Can i transfer player data to another player
I recently had to make a new Minecraft account and I was wondering in my server if there was a way to transfer my old accounts player data to my new one.
TL;DR: Ask an admin but don't get your hopes up
Not too long; did read:
On a server, you can ask an admin (or anyone with access to the server's file system) to replace your current player.dat file with the one for your old account. Most likely though they won't do this unless it's a small server and you can provide proof that you own both accounts.
On a singleplayer world this shouldn't be necessary as your player data is stored in the level.dat file which overrides any player.dat files (even if you're a new account).