click Start-->Control Panel-->Administrative Tools-->Services -->Find out the 'MSSQLSERVER' service,If it 's Status not equal to 'Started', right click it,Select 'Start'..
If it 's Status equal to 'Started',It means SQL Server run normal,So you can use ADO connect to it.If not,Try to close the firewall in Control Panel.
这个不是什么太大的问题 不影响使用,你可以手动输入服务器实例名
我用C#.net链接,连不上,我查不到实例名
例如:SQLEED\Administrator
-->Find out the 'MSSQLSERVER' service,If it 's Status not equal to 'Started', right click it,Select 'Start'..