Restoring an archived Phase allows it to become active and accessible within the Project Schedule again.
Archived Phases and Subphases will display a red archive icon on the status tag.
A single diamond icon indicates a Phase.
A double diamond icon indicates a Phase with Subphases.
Click the three-dot on the archived Phase. Click the Unarchive on the menu.
The Phase will be unarchived. If a Phase contains Subphases, unarchiving the Phase will not unarchive the Subphases within that Phase.