On side navigation bar, access the Control Center.

Choose the "Archived" option from Service Desk section

By clicking on it a new window comes where you can find the archived tickets listed with checkbox on ticket tab.

Once you have selected the Ticket(s), an action bar will appear at bottom of table. Click on the "Restore" button.

A restore confirmation screen will appear. Click on "Restore" to proceed with restoring the selected Ticket(s).