Use Windows PowerShell to restore a farm

You can easily restore the farm using Windows PowerShell. Please follow the below steps as shown below:

1. On the Start menu, click All Programs.

2. Click Microsoft SharePoint 2010 Products.

3. Click SharePoint 2010 Management Shell.

4. To view the backups for the farm, type the following command:

Get-SPBackupHistory -Directory {BackupFolder} -ShowBackup [-Verbose]

5. At the windows PowerShell command prompt, type the following command:

Restore-SPFarm -Directory {BackupFolder} -RestoreMethod Overwrite [-BackupId ]

For More details : http://technet.microsoft.com/en-us/library/ee428311.aspx