ちゃう -とく -てる
Usage
Vてしまう -> Vちゃう This form is used to express an action that has been done completely or to convey regret or disappointment over an action that shouldn’t have happened but did.
Vておく -> Vとく The Vておく form indicates that an action is performed in preparation for something or to do something in advance
Vている -> Vてる describes an ongoing action or a state resulting from a previous action.
Examples
宿題を忘れてしまった! -> 宿題忘れちゃった！
I forgot the homework
ドアを開けておいてください。-> ドア、開けといて。
Please leave the door open (In preparation for something)
本を読んでいる。-> 本、読んでる。I am reading a book