Database cannot be opened due to inaccessible files or insufficient memory or disk space
Msg 945, Level 14, State 2, Line 1
Database 'db' cannot be opened due to inaccessible files or insufficient memory or disk space. See the SQL Server errorlog for details.
Check Microsoft SQL Server error log and determine reason for the cause.
If it is because of a persistent I/O error related to Application Programming Interface, a torn page, or other hardware issues, resolved it and restore it with help of backup. But if there is no availability of backups then try DBCC CHECKDB repair option.
If possible add some disk space to files drive or cleanup some disk space.
Verify the permissions of user account.
Verify if the database is property is set to AutoGrow On.
.mdf and .ldf files should not be marked as Read Only on windows level.
If none of the above solved Issue: Try this
1. Change the database to offline to clear the db status
alter database dbname set offline
2. Now change the database to online, at this step log file and data files will be verified by sql server
alter database dbname set online