You can fix this in Disk Management. Click at lower left on Start, the RIGHT-click on My Computer and choose Manage to open a window. Click on Disk Management.
On your right are two panes, and each scrolls so you can see all its contents. Look at the LOWER RIGHT pane, which has all the valid hardware drives in it, even those Windows can't use right now. Find the second drive you are working on, and it probably does not have a drive letter assigned to it now. As long at its shows that it has a valid Partition with an NTFS File system, you can fix this. Just RIGHT-click on the Partition and choose to give it a drive letter. When done, back out and reboot to update the Registry.