Welcome to planDisney, Monica!
I'm glad you held on to your Disneyland Resort tickets purchased last year, because most tickets have had the expiration dates automatically extended. For example, unused one-day tickets that expired on December 30, 2020 have had the expiration date extended until December 16, 2021. So it sounds like your tickets are good to go! There are just a few things to keep in mind as there have been some changes since the parks reopened.
First, you must link your tickets to your Disneyland Resort account. You can do this on the Disneyland website under the "My Disneyland" menu or by using the
Disneyland app. After your tickets are linked, you need to
make theme park reservations for the day you want to visit. Be sure to check the
theme park reservation availability calendar before making any plans. Everyone in your party will need a valid theme park ticket and a reservation. If you purchased Park Hopper tickets, you will make a reservation for the park you want to start at that day and then at 1:00 p.m. you may hop to the other park (and back and forth if you wish).
I hope this helps! Have a fabulous time at the Happiest Place on Earth!
-Linda