Database Attached failed, Unable to open physical file, operating system error 5: "5 (Access is denied.)" And Version Error

Some times when you try to attach database files (.mdf, . ldf) to sql server , you might get the errors
I     Permission Error
II   Version Error

I     Permission Error

"Unable to open physical file, operating system error" 

This is because of you don't have the full permission for (.mdf) file from where you are accessing. For this reason you need to give the full permission for that file.

1. Right click on file
2  Go to Properties
3. Select Security Pane.
4. Click Edit
5.  Select the Appropriate User Name
6. Give Full control 
7. Apply and Ok

Now you try to Attach the file to Database.

II   Version Error
Some times we can't open mdf file due to lower version of SQL Server. The file will be higher version than the Server version. In that case we need to add supported version where you are loading the file.