In the System Admin Panel, you can recover archived Projects, Studies, Experiments or Project Groups. Open Data Recovery in  the System Admin Panel, open  ELN Recovery then select the organisation and group.

Select from the list the project group, project, study or experiment you want to restore and click Recover. The selected item will be recovered and placed back into the lab’s Experiment Browser from where it has been deleted. In case or recovery of an experiment, the experiment is restored to the original study and project. 

Note that if the project or study is also archived, you will also have the option to recover those to make the experiment visible in the ELN navigation tree. For sample recovery, users can recover samples themselves from the sample archive.