My laptop can't read external hard drives?

The problem may be the usb ports. Try using a usb flash drive, mouse or keyboard to determine if the cause is the usb port.

in addition to the above comments (except the first one) I might add that you could have a faulty USB port. Have you tried plugging it in to a different port?

Or

It could be that youre USB device is trying to use a drive letter that is already taken. By default windows assigns USB devices to the next available letter but it doesnt always work out that way. I had the same thing once where my external HDD was trying to use the same drive letter as my DVD burner. You can resolve this in Disk Management. Here is how to do it.....

http://www.ehow.com/how_4866291_change-external-ha...

You might not have the right drivers for the USB controllers. Do a quick windows update and restart the laptop to see if it works. Sometimes it is just a malfunctioning connection.

If this doesn't work, then have the hardware check by a IT pro.

Top answer: First try unplugging (and removing the battery on a laptop), press the power button for five seconds. Leave it for two minutes and try the USB again. ...

You need to go into control panel; see if there are any symbols like exclamation or question marks showing missing drivers.

IS your laptop reading other devices as well? Check that your USB hub is not disabled. If not try updating it.

Probably you need to install the appropriate drivers.

Probably you need to install the appropriate drivers.

I've got a hard drive that would sort you out my dear

may be your laptop is not installed with appropriate disk drivers.. install them and try again.