Hi,
It is either the LCD screen or the flex cable that connects it to the motherboard that has the problem. Check the flex cable connections in case they have come loose.
Here is a link to the service manual for your laptop. It details how to remove all the various components, including the screen module from your laptop. Hopefully this will help you to isolate your problem. (ignore the title at the top where it says Acer Aspire 5350 Service manual, scroll down and you will see it is the correct one, obviously a typing error).
http://www.manualslib.com/manual/269241/Acer-Aspire-5350.html#product-Aspire 5750G