From where you are, now, you can try rescanning the system to try to find the drive. From the desktop;
1. Right click "Computer" (Vista or newer) or "My Computer" (XP).
2. Select "Manage" from the drop down menu.
3. Click "Disk Management"
4. In the upper toolbar, click Action, and select "Rescan Disks."
If it doesn't find your laptop drive:
1. Is your laptop drive SATA or PATA?
2. How did you connect your laptop drive to another machine? If you used a SATA or PATA to USB adapter, my experience is that various makes of these devices do not always work with every drive and every machine, even when both the drive and the machine are working correctly. It's a known problem with these devices.
3. If your laptop drive is SATA, and the other machine is a desktop, to rule out any problems with a SATA to USB adapter, plug it directly into a SATA connector on the motherboard. SATA is supposed to be hot pluggable, but this varies between motherboards so you may have to reboot to recognize the drive.
PATA connectors for laptops and desktops are different so you would need an adapter between the two to connect a PATA laptop drive directly to a motherboard, and you definitely do not want to try hot plugging it.
If none of the above works, you can try connecting tbe laptop drive to yet another machine or using another SATA/PATA to USB adapter. If that doesn't work, it's probably toast. If the data on the drive is really critical, you could contact a data recover service, but they are pretty expensive so it may not be worth the cost.