Hi Rodrigo, welcome to planDisney!
I have great news! Per
Disney's eTicket Terms & Conditions, any wholly unused, expired Disneyland Resort theme park tickets (except for special event tickets or tickets purchased from a third party), can be applied towards the purchase of a new theme park ticket in equal or greater value to what was paid for the original ticket. So you can absolutely visit the
Disneyland Resort Main Entrance Ticket Booths, and the amazing Cast Members there can help you out!
I also recommend you purchase the
Disney Genie+ service add-on to your tickets. Genie+ gives you access to the
Lightning Lane entrances for certain attractions, allowing you to skip the standby lines! My family and I always purchase Genie+, as it's given us huge time savings from skipping the standby lines. You also get unlimited
Disney PhotoPass Digital Downloads which is a great bonus perk!
I hope you have an amazing time, and if you come across any other questions in the future, please visit us again!
See ya real soon!
Jin