If a colleague rejoins or is accidentally archived, you can easily retrieve the profile from the archive.
Go to
Colleagues > ArchiveFind the colleague you want to restore and open the profile.
At the top, next to your colleague's photo and name, you will see the status 'Archived'. Click on it and choose 'De-archive'.
The colleague is now de-archived and can be found under 'Colleagues'.
Please note: after dearchiving, the colleague's profile gets the status 'Not yet invited'. This article tells you how to invite the colleague again.