Hey there Martina,
Welcome to planDisney and thank you so much for the question!
I definitely can understand how travel plans sometimes have to change. Luckily, the Disneyland Resort makes it easy to change your theme park reservations!
You should be able to change your
theme park reservation on the day of that reservation. I would recommend that you visit the
My Plans hub on the Disneyland Resort website to make this or any other reservation changes that you might need for your trip.
In the event that you're unable to switch your theme park reservation, then Hakuna Matata, Martina! You can still
give a quick call over to a Cast Member at the Guest Information line to get some additional guidance. This is also what you would need to do if your reservation date has passed and you were not able to visit.
I hope that helps, Martina! Thanks again for your question. Make sure to stop by and see us again when you're planning your next Disneyland Resort vacation - we'd love to help!
Have a Magical Day,
Greg