When we graduate from high school, the files will continue to be kept in the school for a short time; Long-term file transfer procedures, high school graduates will hand over files to the local education bureau for safekeeping!
I haven't taken the file since I graduated from high school. On the whole, I still have it. If the university enrolls students after graduating from high school, then the file should be in your university. If you go to a private university instead of a unified entrance examination, then the files should be placed in the local education bureau. The files of high school are generally placed together with the student status, and the education bureau has a backup.
If you need high school files, you can go to the graduating high school to find the corresponding class teacher or grade department director, and you can find out the whereabouts of the files.
I hope my answer can help you!