You borrowed a book from your friend Sarah but lost it.

You borrowed a book from your friend Sarah but lost it. ⇨ apologize for losing the book ⇨ explain how it happened ⇨ offer to replace or compensate for it

Dear Sarah,

I hope you are doing well. I am writing to offer my sincerest apologies for losing the novel you kindly lent me last month. It was a beautifully bound edition, and I know how special it was to you.

Last Friday, while commuting to work, I was reading it on the bus. In my rush to get off at my stop, I accidentally left it on the seat. I returned to the bus depot later that day, but unfortunately, the staff informed me that it had not been handed in to their lost-and-found section.

I feel truly awful about my carelessness. I have already searched several bookstores and online retailers for the exact edition, and I am more than willing to purchase it for you immediately. If I cannot find the same one, I will gladly compensate you for its value.

Once again, I am deeply sorry for this unfortunate incident, and I hope it will not affect our friendship.

Warm regards,
James