From one day to the next
Definition 1 of 2
Pro Tip 1/3Unexpected Events
Use this phrase to describe events that happen without any signs or warnings. 
He was here from one day to the next and then suddenly disappeared.
Pro Tip 2/3Dramatic Changes
Emphasize the impact of changes that drastically alter someone's routine or expectations. 
Her attitude towards me changed from one day to the next.
Pro Tip 3/3No Preparation
Indicates a situation where there was no time to prepare or anticipate the next steps. 
The company's closure happened from one day to the next.