Restore Deleted Site Collection SharePoint 2010/2013

you can easily restore you deleted Site Collection from SharePoint Farm using Powers-shell

Get Deleted Site Collections

Open SharePoint PowerShell and Type following 

Get-SPDeletedSite

it will Return Deleted Site collections.

Restore Deleted Site Collections

Restore-SPDeletedSite -Identity SiteID-From-Above-Screen
After Pressing Enter it will ask for confirmation . Press Y and Proceed.