Hi Medenha, thank you so much for coming to visit us here at planDisney! It sounds like you're planning a visit to the Happiest Place on Earth, so you are in the best place to get help in planning your trip!
You are correct that you currently need both a park reservation and valid ticket or Magic Key pass to enter either of the parks at the Disneyland Resort. If the date you are looking at does not allow you to make a reservation, then that would mean you would not be able to enter the park on that day and instead would need to plan your visit for a different day.
Fortunately, you can check the
Park Ticket Availability Calendar and
Magic Key Calendar to see available reservation dates - both of which are looking very open for the next few months! This is a perfect time to visit the Disneyland Resort as the
Disney100 celebration kicks off on January 27, and
Mickey's Toontown is set to reopen on March 8, so there will be a lot of new and exciting things to do and see during your visit.
Please continue to visit us here at planDisney as you plan your magical vacation! We love to help.
Have a magical day,
Greg