Hi! When you plug your External HD, does the little icon with the green arrow appears on your systray? (lower right corner of your screen) If not, try a different USB port. If Windows still won't recognize it, you might be in front of a non-working device, like the message says. You should've never touched anything inside the case because that won't solve the issue. You can also try this: 1) Go to Device Manager (with the hard drive plugged in,of course) and check if it shows up; if not make a right click on the USB port where the device is plugged in and choose "Scan for Hardware Changes" and see if Windows sees the device.
2) Go to Control Panel>Printers and Other Hardware and on the upper left pane you should have an option "ADD HARDWARE", click on that to start the "Add Hardware Wizard" and follow the instructions to force Windows to see the device. If nothing works, then the external drive is not working or you damaged it. Post back with results,please. Good Luck!
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