I have a problem with my screen

i need to know something,my computer turns on but the screen doesnt,it stays black,can anyone tell me how to solve this or how much money is it worth to fix it?i dont wanna get ripped off,ill come back tomorrow,im really tired right now.

maybe u just hit the brightness adjust buttons on accident F1, F2 by default, might have it set to Fn+F1

no,no,i knew someone would think that,sorry for not being specific last time,but its not the brightness buttons,i hit those and it's not that.I was using it one night and turned it off,when i turned it back on the next day the screen stayed black.What is Fn+F1?is it a way to make your screen stay black?