Nikon D7100 Selective Autofocus Not Working?

So I've had my D7100 for two months now. And since the beginning, I've been using single point, selective autofocus. For the past week or two, it sat on top of my desk untouched and undisturbed. I picked it up last night and the settings were still the same. Tried to start shooting, and the focus point wouldn't move!

I've messed with the settings, reset the settings, took off and replaced the lens, inspected it for any damage, checked the manual, and searched around the Internet for answers, but no luck. The arrows work fine when flipping through pictures, so it's not broken. Regular autofocus works fine, as well. So I'm at a lost. Anyone else experience this? And does anyone know how I can fix it/what I'm doing wrong?

Is it focus point selector locked on the back? Page 75 of the user manual.

At first I was thrown by your "selective autofocus" term as this also has a completely different meaning.

On the D7100, you must be in spot focus or one of the dynamic focus modes (D9, D21, D51, etc). You can't select the focus point in Matrix focus mode. Or in Auto focus mode (these modes are changed by depressing the center button of the A/M switch while rotating the front command dial).

And as suggested above, make sure the focus lock dial is not locked (make sure the outer ring on the mode dial is not pointing to "L"). Also, if the camera is in Auto exposure mode, you can't change the focus point.

I verified these combinations on my D7100.

Some modern DSLR equipment are developing personalities and a few have been know to become quite 'temperamental' after being purchased from the shop only to be placed in the 'display cabinet' or 'left on the shelf'… Perhaps you should stick to buying 'ornaments'