Web app Version
Go to the "Archived Elements
Open the project information panel (i) of the one you would like to restore
Restore your project
Android Version
Open the list of your projects
Display the archived projects
Restore your project
iOS Version
Make sure to enable the display of the archived projects in your settings
Click on the project name to display the list of all your projects
Open the project information panel (i) of the one you would like to restore
Restore your project