ChatGPT 4o made wrong answers completely

Actually ChatGPT 4o is well working. I use to do many works with it and using all it’s features well. When I upload a file and ask some prompts like “read and analyse the file and to ask my answers” and it made very good answers according to my questions. But sometimes it use to give out of resource topics and I as to again prompt it to give from given resource. Ok sometimes it will give answer well but few times it may not.
Now I understood that it is giving answers from it’s data but not provided resources. Only for a few lines it correctly works.
Situation:
Now the situation is very different that I have provided the 3 pdfs of computer networks and used it replied as follows
"“Sat Paul Mittal School Class X & XII Results Analysis”
2. “School Report - Class X 2022-2023”
“Sat Paul Mittal School Class X & XII Results Analysis” - Key Points
Class X (2017-2018):
Total students: 112
Pass percentage: 100%
CGPA Distribution: 10 CGPA (23 students), 9-9.9 CGPA (40 students), 8-8.9 CGPA (30 students), 7-7.9 CGPA (13 students), below 7 CGPA (6 students)"

It gave pdfs don’t have such type of data. To think this capacity problem I used in a well working laptop not phone. Internet is also well working.
Now don’t say it’s pdf problem as it is text document only not images and pdf also don’t have hundreds of pages. Even I have worked with pdfs of more than hundred pages also.

It gave completely wrong information about 3 pdfs. Just nothing matches with the data. I again I made prompts that this pdfs are computer networks pdf. Then giving out of resources data. Here my ChatGPT 4o not completed. So I just made new chat and worked well with same prompts.
Then what is the problem before.