Dear friend,

I am really sorry that I broke your CD. What happened was that yesterday, after you left from my house, I took the CD you borrowed me and tried to play it. But unfortunately, I was in such a hurry that I accidentally dropped the CD on the floor, and all of a sudden, it was broken. I promise that I will try to buy you a new one, and once again, I apologize for my carelessness.

Your friend XX