Help please! I'm losing my mind over here!! My daughter is 11 months and has always had a set…

Help please! I'm losing my mind over here!! My daughter is 11 months and has always had a set bedtime schedule of 10pm-930am until Christmas! Ever since Christmas she has been screaming her head off and fighting sleep until between 1-3 am. Then she'll wake up either at 9am or noon and refuse to nap all day long, idk what to do for her and I'm going crazy!! We've tried letting her cry it out (which worked before) but that's not even helping now, she just screams louder and louder until we get her...