If the BIOS "sees" the unit the issue likely is software or configuration. To start, look in Disk Management and tell us what it says.
To do this, click on Start, then RIGHT-click My Computer and choose Manage from the menu. Choose Disk Management. On the right there should be two panes, upper and lower. Each of these SCROLLS so you can see all they contain. Look particularly a the LOWER RIGHT pane for your second HDD represented by one horizontal rectangle. At its left end will be a bit of info in a label. To the right will be one or more blocks representing Partition(s) on the HDD. For a trouble-free drive, each Partition will have some info showing: a disk name assigned from its initial set-up, a letter name assigned by Windows like...