Go to Device Manager (Win+X, M is the quickest way), and expand the "System devices" list. If you look through the listed devices, there should be an entry for your laptop's lid. Double-clicking this will open the properties panel for that device.
If your laptop supports waking with this particular device, there will be a "Power Management" tab available, and under that tab will be a checkbox to "Allow this device to wake the computer". If the checkbox isn't grayed out, ticking it will allow the computer to wake when the device sends a signal (in this case opening the lid). If the checkbox is grayed out, then your laptop cannot wake upon opening the lid.