Navigate to the Organisation and Users via the Menu.
Click on the name of the Organisation Unit in which the User sits (see view an organisation unit if you're unsure how to do this).
Click on the Users tab.
Change the view to Archived by clicking on the dropdown menu next to the searchbox.
Locate the User that you want to restore by searching for them in the search box or locating them in the list of Users. Click on their Username.
Click on the Archive/Restore link from the Common Tasks tab (you can also click on the Details tab followed by the Archive button if you prefer).
You will be taken to a two-step wizard.
Read the warning message.
Click on Restore.
The LMS will confirm that the User has been Restored.
Click on Finish.