Your guess is as good as mine
You can’t unscramble a scrambled egg.
You can lead a horse to water but you can’t make it drink.
You can’t always get what you want.
You can’t teach an old dog new tricks.
You can’t win them all.
You can’t fit a round peg in a square hole.
You can say that again
You can’t have your cake and eat it too.
Your Guess Is as Good as Mine
