I am sorry your post did not get a reply, Carmen, there were several sub-threads in the thread.
I am afraid little can be judged from the image posted. It does not have any exif data embedded so we can't tell anything about how the image was taken. It is 1024x683 pixels so the number of pixels across the center flower is 93 pixels. Obviously this image is a small crop of a larger image, a conclusion based on how few pixels define the image and how the focus point is outside the frame. Was this flower in the center of the larger frame? The focus point info not displayed in ViewNX2 so the crop may have been to the side of a frame that was cropped out. So the center weight metering would have been of a subject not in this crop. The part of the image that is present is about 1 ev positive bias and when brought down 1 ev and sharpening added, the edges of the petal are actually pretty sharp considering how few pixels define it. The rest of the flower is blurred due to very shallow DOF. Apparently the lens was wide open and had a wide, maybe 1.4 aperture if this was a full image or it could be f/2.8 with a tiny crop, both would give about this same very thin DOF.
That is all that I can tell from this crop, can we see the original uncropped image with meta data intact. A lot more can be determined with the unmodified, uncropped file.

I am sure that this image does not prove evidence that would suggest or disprove a problem with the camera. There is just not enough information contained in the file or in the image content. Given that it did respond positively to adding sharpening is a good sign regarding the functionality of the camera.

Try a tripod shot of a subject with good contrast, in good light, using Matrix metering, AF-S, at 1/100 or faster, with the subject filling 75% of the frame and keeping the meta data intact. That would help you and us cut down on the ambiguity that so many uncontrolled variables create. It might be best to create a new thread. I am sure you will get some good advice.
Stan
St Petersburg Russia

Visit my Nikonians gallery.