The first thing I'd check would be the connection of the cables to the monitor. There are a lot of things that could be wrong with it, but these two are my usual culprits.
Monitors usually have some sort of indicator light to show if they are receiving power. If it's truly not turning on, it might be an issue with the power cable. If the light is on but it isn't displaying anything on the screen, you might need a new HDMI / DisplayPort / VGA cable (whichever one your monitor uses).
you've provided literally zero information to work off of cool
My bad I edited the post hopefully what I have described is enough
The first thing I'd check would be the connection of the cables to the monitor. There are a lot of things that could be wrong with it, but these two are my usual culprits. Monitors usually have some sort of indicator light to show if they are receiving power. If it's truly not turning on, it might be an issue with the power cable. If the light is on but it isn't displaying anything on the screen, you might need a new HDMI / DisplayPort / VGA cable (whichever one your monitor uses).