My GUI stopped working

Ok I fixed it. The problem was with the text. I tried to create new ones and they worked.

I have a main menu with 3D GUI buttons. They worked perfectly until now. I can't press them. I noticed that after I changed the font but changing it back doesn't work.

This is my script.

 var isQuit=false;
 
 function OnMouseEnter(){
     //change text color
     renderer.material.color=Color.red;
 }
 
 function OnMouseExit(){
     //change text color
     renderer.material.color=Color.white;
 }
 
 function OnMouseUp(){
     //is this quit
     if (isQuit==true) {
         //quit the game
         Application.Quit();
     }
     else {
         //load level
         Application.LoadLevel(1);
     }
 }
 
 function Update(){
     //quit game if escape key is pressed
     if (Input.GetKey(KeyCode.Escape)) {
             Application.Quit();
     }
 }