Usage patterns
〈事〉に自信があるto be confident about something
He is confident in his English.
自信を持つto have/gain confidence
Please have more confidence in yourself.
自信を失うto lose confidence
I lost my confidence after failing the exam.
自信をつけるto build up confidence
I built up confidence through repeated practice.
自信を取り戻すto regain one's confidence
She regained her confidence thanks to her coach's words.