If you have not already done so, after restarting, reset the camera by holding the MENU and i (INFO) buttons down together for 3 seconds. These buttons are each marked with a green dot.
Next, if normal operation is not restored, try a "Hard reset":
Remove the battery, memory card and lens (use the body cap to protect the mirror area). Switch the camera ON. Allow it to sit idle for 1 hour. Switch the camera off. Insert the battery & memory card and remount the lens and try it out. If normal operation is not restored then the main circuit board has a faulty component or the image sensor is failing.
Please let me know the result as the memory card issue may be a separate problem requiring additional information for you on how you have attempted to access the photos.
Please keep in mind that my diagnosis & solutions provided are directly dependent on the accuracy of your description of the problem. As with any "do it yourself" fixes, success is a "team effort", since I can't see or touch the camera, and relies on the customer's manual dexterity and ability to follow the instructions well.
If you require additional information, please use the Reply to ExpertTab to contact me. Click the ratings only after our exchange is complete and you are satisfied.
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The card and sensor issues are unrelated. The simultaneous occurrence is, most likely, coincidental.
Do the original photos on the 32gb card still show up when the card is connected to the computer?
Is the metering error message still displayed if the camera mode dial is set to M (manual)?
Remove the lens a fire the shutter. The frame shot should be pure white. If it is not, the image sensor is failing or has failed and you will have to send the camera to Nikon for service using the information at the link below, since a component replacement is required.
As far as the photos on the card are concerned, there are a couple things that can cause the camera to fail to recognize the files. First, if any modifications were made to the photos using the computer, depending on the process used, can render them unreadable. Second, if the files have been moved from the original DCIM folder, the camera will not see them.
You are quite welcome. Unfortunately, some failures do not have any simple user fixes and physical repairs are necessary. Please contact customer service using the drop-down menu to discuss the charges.