No brightness adjustment bar in notification panel?

[AC Question]

No, my phone is not at 5%, yes, the brightness adjustment settings in notification panel is checked, yet still, the brightness slider does not show up. I think I deleted the slider, if that's possible? A few days ago I deleted the miscellaneous files on my phone. It freed up tons of space, although deleted all of my songs... Not a huge problem, though, and I hadn't noticed anything else missing until now. If I did delete it, is there a way to get it back, or would I have to reset the phone to factory settings? Or if neither of these are the problem, does anyone have any other suggestions? Thanks.