Check the front of the lens (glass) first.
You likely have a fingerprint on the top right quadrant of the lens (glass).
Clean with a soft lintless cotton cloth. You can breathe on the lens to add moisture.
To make sure that you haven't accidentally set something that is causing a problem you should reset your camera to factory settings. Look in the back of the User Manual at the index. Look for reset-all.
I got my camera for my birthday last year and it worked fine for a while. Now I'm noticing a blurred left bottom corner on every picture. On auto setting it doesn't focus properly and pictures are over saturated. On AV setting the pictures turn out the same as any other setting (meaning it doesn't focus on one thing an makes the background blurry). Anyone has any idea if this can be fixed with changing some settings or i have to have it fixed by a pro?