As you know I bought a new harddrive and I reinstalled my OS (Windows 7 32Bit). I also reinstalled SQL Server 2008 and Visual Studio 2008. When I try to attach my databases I got "Operating System Error:5". There are two solutions.

1. Right click to the SQL Server Management Studio and click "Run as Administrator".

2."Control panel->administrative tools->services-> SQL Server at the properties and choose "log on as: local system account and also choosed to allo service to interact with desktop".

Second one is worked for me but first one was not work.

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Here is another good video tutorials for SQL Server 2008. It's very useful.

My database take offline itself and I can't change its situation. I restart sql server and sql service but still not working. Then I found a easy and short way. Write this code for take it online. After it goes online immediately take a backup ;)