how the sound was after the editing but accidentaly I saved it.
Maybe how the sound was before editing?
UNDO is only valid while Audacity is open. The instant you close Audacity, it goes around and cleans up all its temporary files and caches like a well-behaved program. Saving an Audacity Project doesn’t help. Projects do not save UNDO.
What you’re supposed to do is Export a perfect quality WAV sound file of the performance before you do anything to it.