Howdy, Andrea! Thanks for bringing your question to planDisney!
I'm so glad you held on to your
tickets that expired in 2020 because most tickets have had their expiration dates extended. Unused one-day tickets that expired on December 30, 2020 will have the expiration date extended until December 16, 2021. If your tickets were part of the promotional 2020 Southern California Resident Ticket offer, those are now good until December 16, 2021 with blockout days of November 20-21, 2021.
To visit the parks, you will want to link your unused tickets to your Disneyland Resort account. You can do this on the Disneyland Resort website under the "My Disneyland" menu or by using the Disneyland app. You will also be required to
make theme park reservations for any day you wish to visit. You can check the
theme park reservation availability calendar to see which parks are available on your desired dates before you make plans.
I hope this helps. Have a fantastic time at the Happiest Place on Earth!
-Linda