“My family is so messy. I am simply going out of my mind. Help me please!”
Most of the time, messiness is a result of lack of storage space. If you can organise some storage solutions, you will find that you are half way there. The rest will boil down to be strict and insisting that until they tidy their mess they cannot get dinner / dessert / go out / do something fun etc! You will need to put your foot down but get organised first so that they cannot have any excuse for not tidying up.