If your monitor is NOT one of those very big things that was somewhat like a TV set, it is an LCD screen.
Most all monitors today are LCD screens. There are however, two types of LCD screens
- Fluorescent backlight
- LED backlight
They stopped making Fluorescent backlight screens some years ago. They last maybe 5 years and then go black because the fluorescent light goes bad. The light is not replaceable
All LCD screens for several years at least now have been LED backlit. LEDs should last many years.
Another thing is that the old screens were a 4x3 proportion format. All the newer ones are 16x9 format.
Bottom line, if yours is one of the fluorescent ones, it is about to die. Otherwise, your monitor will likely outlive your computer and that's fine too.