Controls unbinding.

I loaded up a world and began to play, five seconds after WASD stopped working and you could only use Space or Esc by holding down. I held down Esc and went to controls, I saw that it was set to WASD keys. I tried to set it to WASD again and it didn't recognize the keys. I can't play minecraft, please help!
Ps. It also affected windows users, it affected my friend.