back to the drawing board

(idiom) an idea has to go back to the beginning because it was unsuccessful

Example Sentences:

The boss forced the young employee to go back to the drawing board because his proposal wasn’t likely to succeed.

A: Do you like my idea?
B: No.
A: What should I do?
B: Go back to the drawing board and start again.

From the News:

Rumsfeld sends Pentagon planners back to drawing board over Iraq

Media:

Similar idioms:

1. start something from scratch
2. HPOA
3. HOPA