Once a Contact record has been archived, it is, essentially, tossed into a dark oubliette, never to be heard from again.
But what if you want to hear from them again?
No problem! Users with Admin permissions can view the archive list, and even choose to un-archive records to add them to the pool of active records.
To start, navigate to the Contacts page and click on the "Archived Contacts" button in the upper-right.
On the Archived Contacts screen, you'll see a list of all Contacts who have been archived, with their Contact ID, Contact Name, and Contact Type. Since merging Contacts actually archives one record in the process, you'll see an indication of which records have been archived because of a merge, including the Contact Name of the record that was preserved in the merge process. (The preserved record may have been archived as well, in which case the word "ARCHIVED" will be included in the Contact Name.)
Clicking on the name of any archived Contact will bring up a warning message saying that it has been archived:
But in the upper right, you will see a red "Unarchive" button. Click there to reactive the record.
This will bring up a confirmation message.
Check the box and then click "Unarchive" again to reactive your Contact and bring them back to the land of the living.