Spoiler alert: I am NOT in the medical profession at all and those who dislike getting advice on these threads, please scroll on by.
I stubbed my toe on the bedframe 3 years ago and the nail started coming apart from the nail bed. I stopped wearing nail polish immediately and went two summers with bare toenails, which I didn't like but didn't want to add to the problem by covering it with polish.
I tried everything I could find and yesterday I finally cleaned out my closet and threw away six different items, Kerasal being one of them that did nothing. Keep in mind that the nail will have to totally grow out, I don't believe anything will reattach the nail. l
A friend recommended Tolnaftate 1%, an antifungal cream. I applied to the nail top and around the edges, trying to get some underneath without lifting it. I used it twice a day for about 3 months, cutting the nail as it grew. I finally realized it had completely healed the nail from separating. The cream says it's for athlete's foot so I was wary but IT WORKS!
Vinegar, epsom salts, and peroxide soaks wouldn't do any harm but they didn't do anything for me to heal the separation. Vicks didn't work but I have put it on my feet when I get ready for bed, put socks on top, and my scaly feet have smoothed out. I only do this about once every few weeks because I don't care to sleep with socks.
Good luck, but please try the tolnaftate.