The D5200 has no Focus Mode Switch of its own.
AF-S and AF-I lenses have their own AF Mode switch .
M is manual focus, Turn the focus ring on the lens and look for the focus confirmation dot in the finder.
AF-S and AF-I lenses have their own AF Mode switch as shown HERE>>
These modes select how the D5200 focuses in the near-far axis
You set these Focus Modes by pressing the rear INFO < i > to display the INFO screen. Once the info screen is displayed, press the rear INFO < i > button again to highlight and change the settings.
These AF modes are the second option along the bottom of the INFO screen when you press the rear INFO < i > twice.
I use AF-A, the D5200's default.
AF-A means "Auto Focus — Automatic" mode selection.
AF-A selects between the next two modes. The AF-A mode looks at the subject: if it's holding still, the D5200 locks the focus, and if the subject is moving, the D5200 tracks it as it moves nearer and farther.
AF-S is "AF-Single."
The D5200 focuses once, and then locks AF for you to recompose and shoot.
You can use this for still subjects, but AF-A sets this for you so you don't have to.
AF-C is "AF-Continuous."
The D5200 keeps focusing as the subject moves. Use this for sports and vehicles in motion.
AF-A will set this automatically for you if the subject is moving.
M is Manual focus, if you select it on your INFO screen, you're now stuck in manual focus regardless of how you set your lens.
Turn the focus ring on your lens until the picture is sharp, or look for the electronic "Focus OK" dot on the lower left of the viewfinder.
Set MENU > CUSTOM (pencil icon) > a3 Rangefinder > ON and an additional bar graph will help you focus manually.
AF Area Modes (INFO Screen or Fn button)
These modes select how the D5200 makes use of its 39 AF sensors. Those are the little dots in the middle of the viewfinder.
You set these by pressing the rear INFO < i > to display the INFO screen. Once the info screen is displayed, press the rear INFO < i > button again to change the settings.
These settings are had by adjusting the third item along the bottom.
Once here, your choices are:
[xxx] Auto Area (default)
Auto Area lets the D5200 guess which AF area to use.
In Auto Area, the D5200 almost always gives a great, in-focus shot, only use the settings below if Auto Area isn't guessing the subject properly.
[ o ] Single Point
The Single Point is most helpful for still subjects.
In Single point, the D5200 uses only the AF area you select.
In the Single Point mode, you can select which AF area is used with the rear multi-selector, the round switch with four arrows around the OK button.