I couldnt find my HDD for a while, finally after digging around i found it in the Computer Management area from right clicking on 'my computer'.
It recognizes my SSD as the C drive or 0disk.
But it says my HDD is disk 1 and unallocated, but says its "online"
Try to assign new letter to this disk like this:
Right click “My Computer” =>Select “Manage”=> Choose “Disk Management” => Right click your drive on the list to select "Change Drive Letter & Paths"=> Click “Add” to choose a letter=> “OK”.
If that doesn't make a sense, you might run a free hard drive recovery program that has helped recover all my photos, videos and files from the inaccessible drive for saving your important data and format it to activate it again.