I have .mdf on SQL Server 2008 R2, I work in it almost every day. Today my database hasn't opened without any reason. I appealed to help to my friend-programmer, but he said, that which problem can't be solved by usual methods.
How are you "opening" the database?
As a first step I would try checking database consistency on that database
DBCC CHECKDB (YourDatabaseName) WITH NO_INFOMSGS, EXTENDED_LOGICAL_CHECKS, DATA_PURITY -- , ALL_ERRORMSGS
If there are errors comment IN the
ALL_ERRORMSGS parameter and post the error messages here.
If there are any errors you need to plan to Find & Fix the problem, otherwise it will occur again. Database corruption is most frequently caused by hardware fault - e.g. memory, disk or disk-controller.
if you are in a hurry to have this solved then restore from your last good backup (and run the CHECKDB on that to prove that that backup was "good").
The first thing to do is to look into the main SQL error log. There should be messages there with more details about the problem.
There are multiple reasons why this could happen.
Either a restart of the SQL Server (which is not the case), something in the log was not properly processed, or a real failure in the database (logical or physical corruption) of data. I would say run that command, and look in the Event Viewer for logs coming from MSSQLSERVER source.