Focus ring will not move below 5 feet. Can't focus on things closer than that - AF or MF.

There is a "close focus" limit, depending on your lens. The standard "kit lens" won't focus closer than about 2 feet away. Check that the switch on the lens is set to "AF" not "MF" "MF" means, "manual focus".
When you lightly press the shutter button, the viewfinder should blink with little dots/squares indicating what it focused on, and beep. If it doesn't, and you are set for "AF", then your camera needs repair.

The manual (pg 43) says that each time you press the FOCUS button, it will advance between Auto (AF), Macro (Flower), Infinity (Sideways 8) and Manual (MF). You can use the < or > keys to focus , or the ring if set up as described below:

Next, the focus ring can be programmed (pg 85) by pressing [REC] -> [MENU] -> [REC Tab] -> [Ring Setup]. Choose "CS fps" for Continuous Shutter Speed (pg 46), "Zoom" (pg 40), "Focus" (pg 43), or "Off" for no function at all.

You can download your manual here.

I f this was helpful, please rate it 4 thumbs up. Thanks!

Two methods:-

1. Use the slider switch on the left of the camera to set it to MF (manual focus). The focus ring is an electronic one rather than a physical control like the zoom ring, so the response can seem slow.

2 Go into the camera menu and enable DMF (Direct Manual Focus). This allows you to override the autofocus simply by adjusting the focus control, but it does not work if the slider switch is set to the AF C setting (continuous autofocus), it only work in the AF-S (AF only activates once when the shutter is half pressed).

The 9 you see is the maximum "burst" which is (pictures made in rapid succession) and is not an issue with your problem at this time the flashing green dot is the in focus confirmation light and it's good that you are seeing this as we will use it to remedy the problem.
Diagram


Manual focus switch
Diagram here

What I want you to do is put the AF-MF switch in the manual mode if it's already in manual mode then that was your problem switch to AF and go take some pictures. If it's in AF mode switch to MF make sure teh camera is on and look through the viewfinder at a subject say 15 feet (4.5 meters) away something that has contrast then turn the manual focus ring on the camera slowly until it appears to your ey that it's coming into focus when it's in focus the green light will come on solid, now you know what you are looking for focus an several different objects at different distances and focus manually. Now switch the lens over to AF (auto focus) and focus on the same thing but let the camera do the focusing What auto focus will not focus on in something with little or no contrast like water clear blue sky a painted wall mirror chrome glass and a few other things.
Here is another diagram to check make sure you are in the correct mode.
Diagram

Now for the focus point in the viewfinder make sure it's in the center position.

To adjust the focus point do this

Once you have the camera set to the center focus point and the correct AF mode (one shot) auto focus should return to your camera. Have fun Robert from London Ontario Canada

AF=Auto Focus. With an autofusu capable body, the camera will automatically focus for you using preset focusing zone. Move the Switch to:
MF and it becomes a manual focus lens, where the photographer has to manually focus on his subject.

Which camera are you using? If the body has AF/MF switch, put that also to MF.If this fails to help, take out the lens and try to change it to MF.

Your Sigma 28-300mm doesn't have a HSM-motor as far as i know. When you switch it from MF to AF, you also have to disengage the manual focusing ring by pulling it towards the camera, or pushing it away from the camera. Using the AF without unlocking the manual focusing ring may damage the AF motor. 
I hope this helps, 
/Chris

That is the focusing ring. I'm guessing your camera is set to focus automatically (Little switch on the side of the lens should have settings for either AF or MF, or something similar.)

If its on AF, you don't need to adjust the focus ring.
However, if you have problems with the AF (sometimes it has trouble, especially in low light) you can switch it to MF, and focus manually by changing the ring.

As a general guideline, the more you twist to towards macro, it focuses closer and closer, and infinity futher away (if you're taking a shot of the moon, you want it on infinity)

There are four focus modes: S-AF (Single auto focus), C-AF (Continuous auto focus), MF (Manual Focus), and S-AF/MF (Simultaneous mode). (SINGLE Auto Focus): Focusing is performed once when the shutter button is pressed halfway. C-AF (CONTINUOUS Auto Focus): The camera repeats focusing while the shutter button is pressed halfway. (MANUAL FOCUS): The function allows you to manually focus on any subject while looking through the viewfinder. SIMULTANEOUS USE of S-AF mode and MF mode: You can fine-adjust focus manually by turning the focus ring after AF is performed in the S-AF mode.

This could be due to any of the following reasons. 1) A dirty lens can cause whitish blurring of an image. 2) Light from the flash reflected back from the subject can cause blurring and a feeling that the image is out of focus. 3) In total darkness when AF measurements are impossible, the camera focuses for about 2 meters. Subjects that are closer or further will be out of focus. The Auto Focus Frame is red when AF measurements are impossible. In this case, use manual focus (MF).