No harm done
Definition 1 of 2
Pro Tip 1/3Accidental Context
Use when an accident happens but doesn't cause problems. 
You bumped into me, but I'm fine. No harm done!
Pro Tip 2/3Reassuring Tone
Often said to comfort someone who apologizes for a minor issue. 
Oh, you stepped on my toe? It didn't hurt. No harm done.
Pro Tip 3/3Lighten Atmosphere
Used to lighten the mood after a small incident or error. 
Laughing off the stumble, he said, 'No harm done!'