Date: [Date]
To: [Recipient or role]

Dear Sir/Madam,
I am [Your full name]. You know me through [How the recipient knows you]. I need a recommendation for [Purpose of the document], to be submitted to [Where it will be submitted] by [Requested date].

If you feel comfortable doing so, would you be willing to write a recommendation for me? I can provide relevant work or study details and the submission instructions. Please feel free to let me know if this is not possible.

Thank you for your time.
[Your full name]
[Contact detail, if needed]