Hi there, Elizabeth, and welcome to planDisney!
I'm sorry to hear that your family was not able to make it to the Disneyland Resort, but glad to hear that it sounds like you are all ready to reschedule your trip. This is a great time to visit the parks now that the
Disney100 celebration is in full swing!
Typically, when you purchase theme park tickets from the Disneyland website, it has you log in to your Disney account on the payment screen - so my guess is that they are connected to your Disney account. I do know that you are unable to make a new park reservation for tickets that had already previously had a park reservation attributed to them until that original date has passed (without canceling the original reservation and/or talking to a Cast Member, which I'll cover below).
If you haven't already, the first step I would try is visiting
Disneyland.com to log in to your account. Next, you can hover over "My Disneyland" and select "Ticket and Reservation Details." On the next page, click "View My Park Reservations." Do you see your tickets, now? If so, do they have a park reservation attributed to them? If yes, you can click the "Cancel Reservation" button next to the old dates, and then go you're ready to
make new park reservations.
However, if you continue to run into issues, I would
call to speak to a Cast Member on the Tickets line! I'm confident they would be able to help you get your tickets sorted out so that you are ready to enter the parks with your family.
I do hope that helps, Elizabeth! If you have any follow-up questions as you continue to plan your trip to the Disneyland Resort, please come back and see us here at planDisney!
Have a Magical Day,
Greg