Back to square one
Definition 1 of 2
Pro Tip 1/3Failure Implication
The phrase often implies a failure to progress, requiring a fresh start. 
Our experiments failed; we're back to square one.
Pro Tip 2/3Starting Over
It suggests starting over again, erasing all progress made previously. 
The code has bugs. Looks like I'm back to square one.
Pro Tip 3/3Negative Emotion
It usually carries a negative emotional connotation, indicating frustration or disappointment. 
With the lost contract, it's back to square one for us.