Microsoft SQL Server Management Studio Restore Failed for Server Error

Hi Expert DBA’s,
In Microsoft SQL server Management Studio when I try to restore the server failed to do. The error says the database is in use, but no one is using the database. I do not understand where I went wrong. Please guide me or help me to trap the error. Your help is great. Thanks.

Microsoft SQL Server Management Studio
Restore failed for Server ‘1 1’. (Microsoft.SqlServer.Smo)
Additional Information:
System.Data.SqlClient.Eeclusive access could not be obtained because the database is in use. (Microsoft.SqlServer.Smo)
