Select and hold (or right-click) the unallocated space on the drive, and then select New Simple Volume. If initializing fails for some reason, see A disk's status is Not Initialized or the disk is missing entirely. The disk status briefly changes to Initializing and then to the Online status. If you need to change the partition style (GPT or MBR), see Compare partition styles - GPT and MBR. In the Initialize Disk dialog box, make sure the correct disk is selected, and then choose OK to accept the default partition style. These disks are only formatted and then assigned a drive letter. If the disk is listed as Offline, first select and hold (or right-click) the disk, and then select Online. In Disk Management, select and hold (or right-click) the disk you want to initialize, and then select Initialize Disk. After Computer Management opens, go to Storage > Disk Management.In the search box on the taskbar, enter Computer Management, and then select Run as administrator > Yes.If you can't open Disk Management as an administrator, follow these steps: Select and hold (or right-click) Disk Management, and then select Run as administrator > Yes.In the search box on the taskbar, enter Disk Management.Open Disk Management with administrator permissions. If you prefer to use PowerShell, run the Initialize-Disk cmdlet. The following steps show how to initialize a new disk by using Disk Management. For details, see A disk's status is Not Initialized or the disk is missing entirely. Instead, we recommend troubleshooting the disk to see if you can read the files. If your disk already contains necessary files, don't initialize the disk.

Windows disk management command