Why doesn't my camera autofocus properly?

Do i need a memory card? When i zoom in to capture a good picture it just comes out blurry and not clear. My camera is nikon l310

Two possibilities… One more likely than the other.

One is you're too close to your subject. Your camera has a minimum focus range of about 3.5 feet.
Any closer and the lens can't focus.

Two, you're shaking the camera when the shutter is open causing blur.

Read your owner's manual, learn how to hold a camera still when you're shooting and learn the minimum distance to your subject. Also learn a little about light while you're at it. I'm betting your results improve.

Feet shoulder width apart.
Elbows tucked in.
Right hand on the controls.
Left hand under the lens.
Frame the shot.
Half depress the release and allow the camera to focus.
Take a deep breath - then exhale until you feel comfortable.
Squeeeeeeeze the release in a single, fluid motion - NEVER stab.
Breathe normally once the screen returns to normal.

Also… Make sure you are NOT using the Digital Zoom function of your camera. Go into the Menu and make sure it's turned Off.
ONLY use Optical zoom.