if the vinyl has come away from the backing you might be able to save it by removing the whole roof lining (remove A, B and C pillar covers, trim around sunroof, sunroof winder cover, sun visors and about 4 press-in clips in the centre of the roof lining) and using spray adhesive to stick the vinyl back. dont do it in situ or you'll make a right mess! also dont use evo stick as this can warp the vinyl as i found out!
Its either that or you can go all ghetto and peel the vinyl off the backing, and matt black the backing itself. Dont satin black it or it will look sh!te (also from experience!)
you'd be lucky to find a complete replacement in good condition for sensible money