Turnabout (noun)

1. A change or reversal of direction or attitude.
2. An event or occurrence that marks a turning point.

Origin:

Early 17th century: alteration of turnabout, a noun formed from the verb turn about.

Examples:

1. The company's turnabout from a loss to a profit was seen as a major achievement.
2. The company's decision to switch to a more eco-friendly production process was a welcome turnabout.
3. The speaker's unexpected turnabout during the debate took the audience by surprise.
4. She had a turnabout of heart and decided to help out after all.
5. It was the latest turnabout in a roller-coaster career that has had more ups and downs than a kiddie ride.