They are similar, but can be used in different forms. You can have lost your keys in the kitchen. You can misplace your keys in the kitchen. You can get lost in a forest, but you cannot misplace yourself in the forest.
Misplaced is similar but does not mean lost, its a synomin, misplaced is where you have put keys down but can't remember, and you have a rough idea where they are such as oh yes on the kitchen bench and not on the coffee table , lost is where you have no idea where your keys are and unable to find them.