There are different reasons why we need to restore databases I dont want to go into that,
So There are different options with restores than there are with backups.
The easiest way to demonstrate a restore is to simply restore a database from a full backup, setting the option to overwrite the existing database.
PS SQLSERVER:\> Restore-SqlDatabase -ServerInstance TESTSQL -Database TestDb
PS SQLSERVER:\> -BackupFile "D:\DBBackup\TestDb_db_20140520113014.bak" -ReplaceDatabase