Idiom: "(to) go back to the drawing board" 

Definition:

to start over from the beginning

Examples:

1) After our new business went bankrupt, we decided to go back to the drawing board.

2) My boss told me my idea was not creative enough, so I had to go back to the drawing board.

中文解释： http://www.youzienglish.com/main/idiom_of_the_day/to_go_back_to_the_drawing_board/cn/