When I connect my ASUS monitor to my Dell laptop the ASUS monitor displays nothing instead it says "No Signal"

Hi

You do not say if your laptop screen is working or not or why you want to use an external monitor.

Assuming the laptop has no fault and boots properly, to send the laptop image to an external monitor, once you have booted into Windows, press and hold the Fn (function) key bottom left of your keyboard, near the Windows Logo key, then simultaneouly press the Function key (above the numbers) with the image of 2 monitors, 1 dark, 1 bright (often the F4, F5 or F6 key).

If the laptop's screen is faulty and the above procedure does not work, there may be damage to the graphics card which will probably require specialist repair.

I hope this helps.