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It would appear that the camera part of the Nokia Lumia model in question, is defective at either estimating how to focus, or at longer ranges. Or perhaps it simply has developed a sort of 'nearsightedness', for whatever reason.
Is it still less than a year old? it sounds as if it isn't.
If it isn't, it's a choice between having it serviced (probably just to replace the camera part of it), at your expense if it is out of the warranty period, unfortunately... and replacing it, or giving up on its being a good camera device.
If you want, you could try
1. backing up all data of yours, that are stored on it, onto an external device (e.g. hooking it up to a computer and syncing its data to the computer)
2. doing a data-wipe-and-factory-reset, and seeing if that does anything for the camera on it.