Hi!
You might have liquid-damaged the screen when you cleaned it.
Try shining a flashlight on to your screen to see if only the backlight is the problem. If you can barely see stuff on your screen it's only the backlight that needs to be replaced.
If however you can't see a thing on your screen even with a flashlight, plug it into an external monitor or TV, see if it detects your laptop as a source and shows content. If this works, replace the LCD panel.