寫一封英文信。using formal eng

Dear Madame/Sir,
The purpose of this letter is to express my sincere apologies, on behaving careless to keep a document. The document is given on XX/XX/2007 for (什麼用). I lost it is due to
(Why you lost it?) and as you know, the document is extremely important, so I may want to have another copy to be reserved.I hope that you will find this action acceptable. If not, or if you have any other suggestions, please let us know at your earliest convenience. I am sorry about the incovinence I caused.

best regards.
(name)
(date)

Dear Sir/Madamn
I am writing to report about a document lost. the document of (什麼文件) given by(誰給的) on (給你日子) for (什麼用) was lost on (遺失日子), due to (原因). Please note it in record and advice me on this matter.I would appreciate if another copy could be reserved.Please let me know if you need any further information regarding to this event. i am sorry about any incovinence caused.
I am looking forward to hearing from you as soon as possible

best regards
(名)
(你的dept)