I accidentally delete my Private Member Data. How can I restore this system collection again?
This is the screenshot
The Members/PrivateMembersData collection is the dataset for the Wix Members app, which you can see details of the collection here.
https://support.wix.com/en/article/corvid-wix-members-privatemembersdata-collection-fields
To get it back you will most likely need to delete the Wix Members app from your site and add it back again.
https://support.wix.com/en/article/adding-a-members-area-to-your-site
Finally, note that this is not a code related issue, so you would be much better suited asking this question to Wix Support instead.
https://support.wix.com/en/article/contacting-wix-support
The Wix Corvid Forum is for all code related issues on your site.