PowerShell Script to Restore Deleted SiteCollection from a Webapplication
Get the Specific Webapplication ID and use GetDeltedSites() method to to find out ID your deleted sitecollection and use Restore-SPDeletedSite command let to restore the sitecollection
Add-PSSnapin "Microsoft.SharePoint.PowerShell"
$WebApplication = Get-SPWebApplication
-Identity http://spdev2016:2626/
$restore = $WebApplication.GetDeletedSites()
Restore-SPDeletedSite -Identity 1b0af67e-2f0d-413c-b8b7-9dec119dbc8c -WebApplication 7f1ac80d-d8fb-4a0a-9715-3865a4d139c5
-Confirm:$false
