When did the screen go dim? Did it just start or has it been going dim for awhile?
Don't be embarrassed I cannot even tell you the amount of times I have helped people who have had issues due to cats on keyboards. Most likely what the kitty did what hit the screen dim button. Please look on your keyboard for the F15 key and try hitting that a couple of time which should brighten the display. The F14 key dims the display so I am guessing the cat tapped that with it's paw a couple times.
If this doesn't work let me know as there are a couple other things we can do.
Any change? If not do the following
Choose Apple menu > System Preferences, click Displays, then click Display.
Drag the Brightness slider to adjust the brightness of your display.
If either of those helped please take a moment to rate my service.