My two big toe nails are not attached to the skin under from half to top. there's discoloration. i used mycoster 8% but nothing changed. any advice?

Most likely onychomy: onychomycosis--a fungal infection of the nailbed. If this is the condition, it will continue to worsen. When it hits the nail growth plate, the nail will grow out thick and ugly. This condition may be treated with anti-fungal oral medication like griseofulvin, which is expensive and with potential adverse side-effects. Alternative: paint the nails with colorless tincture of iodine daily.