Dear Bob,
I'm writing to apologize for having forgotten to return the "the Beatles" CD to you when I left Canada,I was in such a hurry that I packed everything in my luggage without checking carefully.Had I paid more attention then,I wouldn't have made such a stupid mistake.
Now something must be done to solve the problem because I understand you cherish the CD enormously.I can either send it to you by express mail or alternatively compensate you at a reasonable price.If you do not mind,I may bring it back to you next time I go to Canada.
Please let me know which solution you prefer at your earliest convenience.I really hope you will accept my sincere apology.
Faithfully yours,
Li ming