Hey there Michael,
Welcome to planDisney and thank you for your question!
Things happen and plans change - I certainly have been there! However, I'm happy to share that you should have a few options here regarding your other tickets.
When
theme park tickets are purchased, they must be used by their expiration date, which is typically a pretty large window. For example, as of the time that I'm answering your question, multi-day tickets purchased today wouldn't expire until January 12, 2026.
After you've purchased those tickets, you then need to make
theme park reservations for each day you plan to visit the Disneyland Resort.
If you end up not being able to make it on a day that you have a theme park reservation, you'll typically need to
call a Cast Member at the Tickets line for help on getting your reservation reset and available for use at a future date.
If, instead, your tickets have expired, you will likely be able to still apply the value of those tickets toward the purchase of new ones of equal or greater value barring a few details like the original ticket type and whether they were used at all.
Again, one of the helpful Cast Members at the Tickets line will be your best next step here to get some more information, so I would recommend having your ticket information available to share with them when you call so they can look up the details.
Thanks again for your question, Michael! I hope you have a fun time making new memories at the Happiest Place on Earth.
Have a Magical Day,
Greg