no worries
1. That is not a problem; don't worry about it. A: "It looks like the file was deleted when the computer crashed." B: "No worries, there should be a backup copy." A: "Sorry about last night, I was out of line." B: "No worries, man. I know you didn't mean it."
2. I would be happy to. A: "Would you mind emptying the dishwasher for me?" B: "Sure, no worries."