Can’t Switch Fn Keys Back to Multimedia Keys

I have been using Dell Inspiron 15 5567 i7 since August of 2017. On January 3, 2017 I restarted my laptop for Windows updates. However, when I began to use the laptop after the restart it became apparent that the multimedia keys (volume, brightness, play/pause, etc.) weren’t working. It appears that during the restart, the top row of keys somehow changed from primarily acting as multimedia keys to primarily acting as function keys. This change is unwanted and quite inconvenient for me.

I’ve spent a fair amount of time searching through options and settings in Windows Control Panel and Windows Settings and haven’t found anything related to the function of the multimedia/Fn keys. I’ve gone to the BIOS settings three times and not only is there nothing related to the multimedia/Fn keys, but my BIOS doesn’t seem to have the same configuration and options as the online examples. I have accessed BIOS both by pressing shift while selecting restart and by pressing F2 when the Dell screen appears when restarting. Finally, the Fn-lock key (Fn+Esc) does not seem to have any function at all.

I feel that I’ve exhausted all of the obvious options and all of the options I can easily find online. I would greatly appreciate any help in figuring out how I can switch the Fn keys back to performing as multimedia keys. Have I looked over something? Am I not properly accessing BIOS settings? Please help.