How to get a nikon d3100 pictures to not be blurry?

I just got my Nikon d3100 a few days ago and it seems to be very blurry now. The pictures are not nearly as good as they were yesterday. How can i get them back to the way they were before?

If you have the mode set to auto, it can be due to a couple reasons.
The sure fire way to not have blurry pictures is to have your camera mounted, like on a tripod to eliminate shaking.
Otherwise, better lighting will result in the camera having a faster shutter speed and a smaller aperture setting. This results in a clearer photograph.
Flash would help too.

Stop using Live View and learn to hold it properly.

Play with the interactive SLR simulator linked below. It will give you some tips as to how your pictures might be coming out blurry. Get your camera out and experiment with the settings.

Also make sure you haven't turned off the AF on your lens, and that you haven't accidentally selected the wrong AF point.

Provided you have not already dropped it, a DSLR does require a learning curve to get the best out of it. This could take anywhere from a few hours to 50 years, depending on your knowledge of photography.

Until you get the grasp of it, put your camera into Auto or Guide and see if that helps.

Many lenses also have a switch that you can turn autofocus on or off. Make sure you have not turned it off.

Really? If you're using live view, stop doing that. Take the dang camera out of full auto and read some basic photography books. The camera is not broken and none of this is the cameras fault.

Try taking the protective film off the lens.

All cameras have to be rock steady whilst the shutter is open, It will be especially important in low light when shutter speeds of necessity will be longer, I mean absolutely solid. Don't use live view, then read the page in your manual about how to hold the camera properly, the thing everybody thinks they know and ignore. Then practice it, it's a skill you'll need to learn. And I'm really not being condescending, just watch a Pro photographer at work.

It would be nice if you can put a photo on line (pref www.flickr.com) so we can see it. The exif data tag with the picture can tell us a lot about the settings on the camera.

there are two possible problems:

You have the lens on manual focus, check out a little switch near the underside of the lens AF/M

Your focusing area may need changing. I find when using telephoto that spot metering is best as the camera does not know quite what to focus on otherwise