Seems images are better way to answer this question.
- Projects are greyed out when you ignore them in your IntelliJ workspace.
- To add those projects or modules back in your workspace, right click on them and click on unignore projects as shown in below screenshot.
- Alternatively, you can also go to File – Settings -> Build, execution and deployment -> Build Tools -> Maven -> Ignored Files, now select whichever projects/modules you may wish to retain in your IntelliJ workspace.
