If you ordered invitations from Minted and you had to change your wedding date, they are offering to reprint for 25% of the price originally paid for your order. Just go to their website and chat with customer service.
We also ordered a photo guestbook from Artifact Rising and they offering to reprint at no cost.
May be a good idea to check with all the vendors that you ordered from with your wedding date printed to see what they offering! Just some positivity in all the chaos of rescheduling. Good luck to everyone!