My laptop screen is broken and external monitor is not working suddenly.(Blank screen appears)?

I'm using Lenovo G450 model laptop, OS is Windows 7, suddenly my laptop display got damaged and now I'm using external monitor to work and it was working till yesterday without any problem, today I restarted my laptop and pressed F8 during restart, suddenly external monitor's display got blank and only green light of the external monitor is blinking, nothing appears, I'm unable to see any options too, I have restarted many times but nothing happened, kindly help me please. Thanks in advance. NOTE: I can't see any boot screen via external monitor, I can see direct desktop if everything goes well. Now simply blank screen is displaying with blinking green light on external monitor.

I can't say for sure but I suspect a driver issue. Some laptops can't use external monitors in safe mode, for example. I can only speculate but a replacement screen is pretty inexpensive. A quick search gave me prices from $10-50. You can search that model number to find a video on removing the screen. It is not difficult. Then you can get the specific screen part number for ordering.