How to op myself

[oscarnorman]

So I started a ultra modde survival game and I played for a couple of hours, ran 1500 meters away from the start point, somehow managed to destroy my bed and I spawned 1500 meters away from my home and there is no chance I can go back except if I could use the creative command, but I cant for some reason, it just says "You dont have permission to use that command", please help me I would really aprecciate that!

-Oscar

The reason to why there is no chance of getting back is because of all the mobs that keeps killing me on the way bay

[oscarnorman]

bump

[planetguy]

Open the level.dat file with a NBT editor and change allowCommands to 1. You will then be able to go on creative mode.

[Poseidon5001]

Try this,
Open to LAN, with Cheats enabled, or do what planetguy said.