It's probably a third party lens. Can you focus manually and see if you can bring subject into a sharp focus? You'll probably want to perform a master reset before messing with settings. There's not telling what custom options are set.

To do this, refer to manual page 76. You can download the manual from Nikon's support page.
Basically, you push CSM and MODE button simultaneously and hold for 2 seconds.
Then, Do the same thing again. Release one of the two buttons while CUSTOM is blinking, then press both buttons again.

The first steps will reset settings to a default value. The second steps will clear custom setting.

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