“Non, je ne regrette rien” (no, I regret nothing) was written by Charles Dumont and Michel Vaucaire and recorded by Édith Piaf in 1960. She looks back on everything — the good done to her, the bad, the loves, the troubles — and sweeps it all away. She's paid for it, forgotten it, and she's starting again from zero, because her life and her joys begin today, with a new love.
Piaf, frail and ill by then, sang it as a defiant comeback, and it became one of her most famous songs, later used in countless films.
The French is slow and very clearly sung. Learn the key structure “ne… rien” (nothing) and the verbs of letting go: oublier, balayer, repartir.