Need help with Toshiba Laptop. When searching something up on google i pressed a button which made my screen look dull.

[xXBoyBlockGamerXx]

i have a toshiba and something happened, i pressed a button, maybe F4, and now dont know how to change it back! Plz help

 

[xapoc]

I think pressing function key (Fn) + shift will cycle through screen resolutions.
try
F4 is for hibernation