Well, major bookstore chains like Barnes & Noble might carry it. Or you could try searching on the official Naruto manga website to see if they have any purchase links or recommended retailers for the box set.
The contents of the solo levelling manga box set typically consist of a series of manga volumes. Some versions may even throw in limited edition prints or exclusive interviews related to the series. However, the exact inclusions can differ based on the publisher and edition.
If not under warranty, you could try to fix it yourself if the damage is minor. Maybe some glue or tape could do the trick. But for major damages, it might be best to look for a professional repair service or consider buying a new one.
The box set usually contains multiple volumes of the D Gray Man manga. Sometimes, it might also come with special extras like posters or character cards.