there could be a few issues here.
1. backlight may have gone out how you can check:
Take a flash light to the display if you see something then its your back light,
2. Power supply inside the unit, unplug the unit take the back off then uncover the shoud that covers the power supply and check for bulging capacitors if you have bad capacitors this can happend as well.
3. check the monitor with another computer and so forth.
Ok i start with the worse to the least cause of your issue, i hope this information does help please do make sure you leave your ratings for your advice before you leave. Btw, I’m available to help over the phone in case u need at
https://www.6ya.com/expert/edwy_1a56970cf1ea4620