When i create a world and build a tardis and then leave the world. Then when i play the world my tardis wont let me in. It says ''you dont have the permission to enter the tardis, this tardis belongs to Player'', but my name in the game IS Player. SO WHAT THE HELL! I hope there's a explanation for this.

Hello, are you by chance running on a cracked / free / offline copy of the game?

oh okay thank you for your help

i have an offline copy of the game. thanks for your help

In that case it's because everytime you join the game a new UUID is created for your player. (This doesn't happen on a genuine / online version of the game)

Tardises store the owner data using UUIDs this would explain why you're getting this message as the UUIDs form each game session do not match. Hope this helps

thanks mate