Hard drive bug?

Question

Windows

In general, I installed Windows on a new computer and during the partitioning of the disk I split it into 2: one for the 300GB system, the other for my 700GB needs (the hdd itself was 1trb).
And when Windows got up, it turned out to be only a 300GB C drive, I wonder where the second one disappeared ?? Is it possible to fix this somehow without reinstalling Windows (even the computer does not see this flash drive with Windows during boot, although the priority is set)

Answer 1

Start -> Run -> diskmgmt.msc
There, format the second partition and assign a letter to it.

Answer 2

Log on with an Administrator account or a member of the Administrators group.
From the Start menu, select Control Panel, and then Performance and Maintenance.
Note. If Performance and Maintenance is not displayed, go to step 3. Performance and Maintenance will not appear in the Control Panel until you switch to Category View. When using the classic display mode, Performance and Maintenance is not displayed.
Select Administrative Tools, double-click Computer Management, and then click Disk Management in the left pane.
Most likely you did not create disk 2, so Windows does not see
microsoft.com