Don’t have permission to access SQL Server Express 2008?

Sounds like the account you are logging in as does not have the rights to perform these options. To give yourself these rights, you will need to log in as an administrator, or the SA account (if mixed mode is enabled).

When you're logged in as the administrator, then you should be able to assign yourself the appropriate privileges to be able to restore databases using your own user account.

The solution, that actually worked for me published by the author Blipsolt:

1. shut down SQL Server from services

2. open cmd window (as admin) and run single-user mode as local admin with this command

   c:\Program Files\Microsoft SQL Server\MSSQL10.SQLEXPRESS\MSSQL\Binn\sqlservr.exe" -m -s SQLEXPRESS

3. open another cmd window (as admin)

4. open sqlcmd

   sqlcmd -S .\SQLEXPRESS

5. Now add the sysadmin user:

   1. sp_addsrvrolemember 'domain\user', 'sysadmin'

   2. GO

6. Ctrl+C the single-user mode from the first cmd window to kill SQL Server.

7. Restart it from services the normal way.

8. Log into Management Studio and the user you created should be listed under logins with the credential of "sysadmin."