[Your Name]
[Your Address]
[City, State, Zip Code]
[Email Address]
[Phone Number]
[Date]

[Recipient Name]
[Recipient Title]
[Company Name/School Name]
[Company/School Address]
[City, State, Zip Code]

Dear [Recipient Name],

I am writing to sincerely explain my absence from [work/school/event] on [specific date(s)]. Unfortunately, [briefly explain the reason, such as a sudden illness or unexpected personal matter] required my immediate attention, and I was unable to fulfill my responsibilities as expected.

I regret any inconvenience my absence may have caused and want to assure you that I am taking steps to catch up on any missed work. Please let me know if there are any specific tasks that need my attention.

Thank you for your understanding and support during this time.

Sincerely,
[Your Name]