Commands not working

Are cheats enabled?

Those commands are incomplete; try "/gamemode creative", for example.

Yes Cheats are enabled. I was working on texture pack and commands worked fine, after i re-entered the world nothing worked expect /seed. I tried disabling texture packs, reloading the world, reloging nothing helps, but in other worlds everything is okay. I don't know what cause this weird bug.
@LunizIsGlacey, i tried it still doesn't work.

When you open the world, does it say "Cheats" in the third line on the "Select World" screen? If not, cheats are not enabled.
On Multiplayer make sure you are opped.