Formal:
* Recommencer: This is the most common and literal translation of "start over."
* Reprendre: This means "to take up again" and can be used in a formal setting.
Informal:
* Repartir: This means "to start again" and is a more casual way to say "start over."
* Recommencer à zéro: This literally means "to start again from zero," and emphasizes a complete restart.
Examples:
* J'ai fait une erreur, je dois recommencer. (I made a mistake, I have to start over.)
* Je suis prêt à reprendre ma vie à zéro. (I'm ready to start my life over from scratch.)
* On repart de zéro? (Shall we start over?)
The best way to choose the right expression depends on the specific context of your sentence.