Missing two of your favorite web parts? Don’t fret.
Make sure the site collection feature “SharePoint Server Publishing Infrastructure” is activated
Make sure the site feature “SharePoint Server Publishing” is activated
Still not there? Check “Settings” in the admin center to see if custom scripts are allowed on personal and self-service created sites (allow both). This can take up to 24 hours to take effect.
If you can’t wait (and you’re using SharePoint Online), use PowerShell to make the change immediately, changing my site details to your own
$UserCredential = Get-Credential -UserName $adminUPN -Message "Enter password"
Connect-SPOService -URL https://sharepointlibrarian-admin.sharepoint.com -Credential $userCredential
Set-SPOsite https://sharepointlibrarian.sharepoint.com -DenyAddAndCustomizePages 0
Repeat the last line for each site on which you need to quickly activate this setting. For example, I would run it again on https://sharepointlibrarian1.sharepoint.com/sites/AnotherSite
Your web parts should have now returned! Good luck.