Is my nose fixable, what has caused this hollow depression? (Photo)

I recommend getting a consultation to go over your concerns and your desired results. Revision rhinoplasty is a technically challenging procedure and I would suggest that you seek a surgeon that has a good track record for natural results.  There a few select of these surgeons in each major city.  I would look at their reputations, board certifications, and before and after pictures.  
I hope this helps.

HI - the depression appears to be due to your tip cartilages rotating to your right (left in photo)...probably because tip isn't supported well enough.  This has created relative fullness on your right and relative depression on your left.  I would recommend an open revision with rib graft to straighten and support your tip, and temporalis fascia as your nasal skin is thin...the fascia acts like a blanket to camouflage edges of cartilage