Try this model.
Date:
To
Name of the employee
Employment No/ Department/ Division
Dear Sir/Madam
SUB: Not Reporting to Duty
This is to inform you that you are remaining absent from duty w.e.f (dd/mm/yy) without any intimation.
Please be informed that absenting without intimation is misconduct vide clause (clause No.) of the Standing Orders of the company. Therefore, you are likely to lose your lien on the employment contract, and your services may be terminated without notice from our side. You are hereby advised to report to duty immediately and provide reasons for your absence without intimation. If you do not return within two days of this notice, we will be forced to terminate your employment without further notice or inquiry.
Manager (Personnel/HR)
Copy to: General Manager
MD/CEO