SharePoint Online: How to Restore a Deleted Site Collection using PowerShell?

Requirement: Restore a Deleted Site Collection in SharePoint Online.

How to Restore a Deleted Site Collection in SharePoint Online?
SharePoint Online recycle bin provides the ability to recover even when an entire site collection is deleted. To restore a deleted site collection in SharePoint Online, follow these steps:

• Login to SharePoint Online Admin Center >> Expand Sites >> Deleted Sites. This page lists all deleted site collections.
• Pick the one you want to restore and click on the "Restore" button from the ribbon. 
• You'll get a message "Site Restored" once the restore operation completes.

Restore a deleted site collection SharePoint Online from classic admin center:
Similarly, to restore a SharePoint Online site in the classic admin center:

• Click on the "Site Collection" link in the left navigation.
• On the ribbon, click on the "Recycle Bin" button. You'll see the list of all Site Collections which are deleted along with when they were deleted, and how many days are remaining before they disappear from the recycle bin.
• To restore deleted site collection, Select the site collection that you want to restore in the Recycle Bin page, click on "Restore Deleted Items" button in the Ribbon.
  
• Click on the "Restore" button in the Popup window to restore the selected site collection.
  

The default retention period for deleted items in SharePoint Online is 93 days! However, this applies to classic sites only! you have up to 93 days to restore. For modern group connected site collections, the retention period is limited to 30 days, as enforced by Azure AD recycle bin settings.

SharePoint Online: PowerShell to Restore a Deleted Site Collection
When a SharePoint Online site collection is deleted, it is placed in the recycle bin, then it is permanently deleted after the retention period. Recovering a SharePoint Online site is quite easy. Here is the PowerShell to restore the deleted site collection.

Step 1: Connect to SharePoint Online from SharePoint Online Management Shell

#Config Parameters
$AdminSiteURL="https://crescent-admin.sharepoint.com"

#Get Credentials to connect
$Cred = Get-Credential

#Connect to SharePoint Online Tenant Admin
Connect-SPOService -URL $AdminSiteURL -Credential $Cred

Step 2: Get a List of All Deleted Site Collections

#Get All Deleted Sites
Get-SPODeletedSite

Step 3: Restore the Site collection from Recycle bin

#sharepoint online restore deleted site powershell
Restore-SPODeletedSite -Identity "https://crescent.sharepoint.com/sites/Vendors"

That's it. Your site should be back! We've restored SharePoint Online site collection using PowerShell. If you want to permanently delete a site collection, you have to delete it from the recycle bin as in SharePoint Online: Delete Site Collection from Recycle bin using PowerShell

Restore Deleted SharePoint Online Site using PnP PowerShell 
Let's recover deleted site collection in SharePoint Online using PnP PowerShell.

#Config Variables
$TenantURL = "https://crescenttech.sharepoint.com"
$DeletedSiteURL ="https://crescenttech.sharepoint.com/sites/Purchase"

#Connect to PnP Online
Connect-PnPOnline -Url $TenantURL -Credentials (Get-Credential)
 
#Get Deleted Site from Recycle Bin
$DeletedSite = Get-PnPTenantRecycleBinItem | Where {$_.URL -eq $DeletedSiteURL}

If($DeletedSite)
{
    #restore site collection sharepoint online powershell
    Restore-PnPTenantRecycleBinItem -Url $DeletedSiteURL -Force -ErrorAction Stop
    Write-Host -f Green "Site Collection '$DeletedSiteURL' Restored Successfully!"
}
Else
{
    Write-host -f Yellow "Could not Find Deleted site:"$DeletedSiteURL
}

This PowerShell restores the deleted site in SharePoint Online!