Lost mail correspondence from IRS, how to get a duplicate copy?

[Anonymous]

My USPS Informed Delivery showed a letter from the IRS with my address and name.  The letter was never delivered.  The PO shrugged when I went looking for it.

Irs.gov showed nothing under "Notices and Letters".  I had both email and paper selected for communication.

At this point, how do I go about getting a duplicate letter?  Who do I call?  

Thank you!

[Critter-3]

Call the IRS at 800-829-1040  between 7 AM - 7 PM local time Monday-Friday

• Choose # for language preference, then listen for brief recorded message about refunds. 
• When prompted, choose option 2 for "personal income tax" (DO NOT choose option 1, "Refund" or you will be sent to an automated line/message and have to start over)
• Next, press the following sequence in order - 1, 3, 2 
• You will then be asked to enter your SSN or EIN twice.  DO NOTHING - JUST WAIT until new menu options are presented.
• Then, press 2, 1, 3   Unless call volume is excessive (at which point you will hear a recording and be disconnected), this sequence will put you in queue for an agent to assist with providing details of an existing payment or installment arrangement.