When your database partition is full, the Microsoft SQL server sets the status of the database that can no longer grow to “Recovery Pending”. This status means that SQL can’t open the database and can’t lock the database files. This status is comparable to a database in offline mode.
Another cause is with problem with the drive. The drive is either missing or miss configured.
Run the following will either fix the database or tell you the problem…
ALTER DATABASE [MyDB01] SET ONLINE
If it is a drive or file issue, fix the drive or file issue and restart SQL Server.