Do you mean that code won't work? if so heres why, you don't need to escape the quotes (\") instead just use single quotes around the variable. you also need a ; at the end of the line (inside the quotes).
For example:
$sql = "UPDATE phone_numbers (userID,number,password)
values ('$userID', '$number', '$password');";
$result = @mysql_query($sql,$conn)
A better way to do it though would be
$sql = "UPDATE phone_numbers set 'userID' = '$userID', 'number' = '$number', 'password' = '$password';";
$result = @mysql_query($sql,$conn)
You also need to find the old entry to adit, so assuming you have that info stored as $old_userid, you need to add "where 'user_id' = '$old_userid'"
Full code:
$sql = "UPDATE phone_numbers set 'userID' = '$userID', 'number' = '$number', 'password' = '$password' where 'user_id' = '$old_userid';";
$result = @mysql_query($sql,$conn)
