It is easier to find the things you need if your room is tidy.
If they are all over the floor, you risk breaking and damaging things.
If you put your dirty clothes in the washing, they will be able to be washed, and be ready next time you want to wear them.
If you have food scraps in the room, they may go mouldy and smelly, and may attract vermin.
It is much more pleasant to be in a tidy room, with your special pictures and possessions on display.
It is a much more pleasant place to entertain friends, if it is tidy.
It is much more pleasant to dry yourself on a dry, fresh smelling towel, than a wet musty smelling one. Your body will pick up the musty smell from the wet towel, and you will smell like that all day.
Your mother will feel less resentful if you show you have made an effort, and will be more inclined to do you favours.