expression, godan verb (-ru)
go back to square one; make a fresh start; be back where one started
Idiomatic expression meaning to return to the starting point after an effort fails, or to begin again from scratch. Often used when plans, negotiations, or projects fall through.
See also: 振り出し
交渉が決裂して、計画は振り出しに戻った。
The negotiations broke down, and the plan went back to square one.
The data got deleted, so I have no choice but to go back to the beginning and start over.