A basic or dynamic disk's status is Unreadable.
Cause:
The basic or dynamic disk is not accessible and might have experienced hardware failure, corruption, or I/O errors. The disk's copy of the system's disk configuration database might be corrupted. An error icon appears on disks that display the Unreadable status.
Disks might also display the Unreadable status while they are spinning up or when Disk Management is rescanning all of the disks on the system. In some cases, an unreadable disk has failed and is not recoverable. For dynamic disks, the Unreadable status usually results from corruption or I/O errors on part of the disk, rather than failure of the entire disk.
Solution:
Rescan the disks or restart the computer to see if the disk status changes. For instructions describing how to rescan the disks, see To update disk information.