acer notebook help needed asappppp!!

I have an acer 1410 notebook. The screen is constantly dimmed so I can barely see a thing and it is unusable the warranty is up and I’ve had the laptop just over three years. I’m 15 so not having a laptop to do essays and revision for gcses is a major problem that needs fixing quickly. It is not on my settings dimmed so it shoulld be bright. I have tried the fn key and arrows and still no luck.if someone could suggest what is wrong and whether it is worth fixing or not and if so how much it will cost I would appreciate it. It used to go dimmed if the screen got knocked but now its permanent. Many thanks for ANY suggestions 🙂