I always tell my daughters never to put any 'media' items in the loft, cellar or garage because hot, cold and damp will damage them. That includes vinyl, CDs, DVDs, photographs, negatives, videotape, cine film. The problem is that these are the places where we store things. I suppose the important thing is not to put anything irreplaceable there.
Anyway, I googled can warped vinyl records be repaired and there are some suggestions involving heat. You would do best to google that yourself so you can choose which method suits you. There are videos on You Tube as well.
Three methods are shown here:
www.wikihow.com/Fix-a-Warped-Vinyl-Record
