Why did one of my eyes sink in and how can I fix it with home remedies? (Photo)

smadeo89 thank you for the picture and  and questions.  From your one picture alone you have an asymmetry between eyelid and brow position.  There are numerous  reason that this can occur;  unfortunately none of which are corrected by home remedies.  An in person consultation is necessary to determine your best course of action.  It would be best to be evaluated by An Ocular Plastic Surgeon

See an oculoplastic specialist for evaluation. If the sunken appearance is only on the outside (upper eyelid), then filler injection is a good treatment; see following video and link. But you want to make sure the whole eyeball is not getting sunken. 

Thank you for your question.  Unfortunately, this question is difficult to answer with just only one view. Just looking at the photo, your right brow appears to be slightly more elevated than the right.  The sulcus of your right upper lid is deeper, thus more visible.  Your lower lids are more symmetric, however, you demonstrate some scleral show. Meaning, the margin over your eyelid is not at the junction of the white and centrally colored part of your eye.  This can happen with aging as the structures in the eyelid weaken over time.  There are numerous other causes, one being the eyeball is pushed out of the globe (exophthalmos).  
The asymmetry could also be the result of a masked ptosis (drooping lid).  A good place to start would be to have a consultation with a plastic surgeon or ophthalmologist that specializes in eyelid surgery. In other words, before any therapy, it is important to have a evaluation by an experienced surgeon to make the correct diagnosis.
Sincerely,

Nicholas Jones, MD

It is quite frankly  a strange history in the absence of any trauma to the eye for and eye to "sink in".  This would imply some loss of substance in either the eye socket  or the eyeball itself.  You need to see an opthamologist to quantify what is going on.... Old photos prior to this appearance might be helpful to determine how much is real or not.  Alternatively, when looking at the eyes, the left globe [eyeball] is more prominent, with a bit more scleral show [ which means more white of the eye is showing] and may actually be the problem in appearance.  A unilateral proptosis [eye pushing forward] may be the issue... and may be caused perhaps by some abnormal opthalmolgical problem.  Lastly, in the absence of any disease process of the eyes, asymmetry is not uncommon.  
The bottom line :  Get a complete and thorough eye exam.....good luck
Armand Simone, MD FACS  New york, NY
Senior Plastic Surgeon

There is no home remedy to fix eye asymmetry. See an oculoplastic surgeon for a proper and safe evaluation. Best of luck!

Sunken eye is very are and needs to be evaluated if it is truly sunken.  Often a small ptosis gives the impression of sunken eye or if the other eye comes forward , it also gives the impression of sunken eye in the opposite eye.  I suggest that you see an oculoplastic surgeon who can evaluate the true nature of your problem and guide you to the right treatment.