Dear <concern>,

Hope you are doing well.

Unfortunately, I have lost my access card and hence using visitor card to get in and out of office from Jan 5, 2018.

Despite of searching at home, office and other possible places, I could not find it.

Hence, please consider this email as formal request to re-issue my access card or let me know the process I should follow to get the new one.

I apologize for inconvenience and assure to handle it with care going forward.

Kindly let me know if you need more information in this reference.

Yours Sincerely,
<employee name>