error loading a user record with php

Greetings, when I run an application on my PC I do not have errors but when loading it into a hosting when wanting to make a record it tells me the error:

  

Fatal error: Call to undefined method userDao :: query () in /home/ufajardo/public_html/archisoft/modelo/dao/usuario/usuariosDao.php on line 81

static function  registrarUsuarioDao($apaterno, $amaterno, $nombre, $usuario, $clave, $tipo, $status){
  $datosArray=array($usuario);
  $st=  procesaParametros::PrepareStatement(usuariosSql::validateIfExistsUser(),$datosArray);

  $query=self::query($st);
  //$query=$this->con->query($st);

  if($query->num_rows==0)
  {
    $st = "INSERT INTO usuarios(apaterno, amaterno, nombre, usuario, clave, tipo, status, fRegistro)
    VALUES('$apaterno', '$amaterno', '$nombre', '$usuario', '$clave', '$tipo', '$status', NOW())";

  $query=self::query($st);
    //$query = $this->con->query($st);
    $result = Notification::registeredRecord($query);
  }
  else
  {
    $result = Notification::existsUser();
  }
  return $result;
}

The comments are because I change that code for the new one, because it gives me this error:

  

Fatal error: Using $ this when not in object context in /home/ufajardo/public_html/archisoft/modelo/dao/usuario/usuariosDao.php on line 82

line 81 is: $query=self::query($st)

line 82 is: query=$this->con->query($st)