The certificate, asymmetric key, or private key file is not valid or does not exist
Here are the steps that I had to take to restore the encrypted database onto a different server(localhost).

1.Create the certificates :

CREATE CERTIFICATE [CertficateName] 
FROM FILE = 'C:\FolderName\NameOfCert.cer'
WITH PRIVATE KEY ( 
    FILE = 'C:\FolderName\NameOfCertKey.key' ,   
    DECRYPTION BY PASSWORD = 'YourPassword'
);


2.

USE Master ;
Open Master Key Decryption by password = 'YourPassword'
Backup master key to file = 'C:\SQL FodlerName\MasterKeyName.key'
        ENCRYPTION BY PASSWORD = 'YourPassword';
    GO


3.Restore Master Key

Use master 
    restore master key
    FROM FILE = 'C:\FolderName\MasterKeyName.key'
    DECRYPTION BY PASSWORD = 'YourPassword'
    ENCRYPTION BY PASSWORD = 'YourPassword'


4.
This is the last step you ,be careful at this stage as it took me a while to get that each command needs to be run separately :

Alter Database [DatabaseName]
SET SINGLE_USER WITH
ROLLBACK IMMEDIATE


Next run it separatly 

USE MASTER
OPEN MASTER KEY DECRYPTION BY PASSWORD = 'YourPassword';


Next command run separatly

RESTORE DATABASE [DatabaseName] FROM DISK = 'C:\Folder\FULL\NameoftheBakFilethat ourAreRestoring.BAK' 
WITH Replace , STATS = 5 


Do not forget to set back to Multi-User mode the Dabase.