I just made a major mistake by deleting a recurring event every week. This deleted all my past appointments. I have a valid calendar saved on a memory stick but not sure how to update my calendar. It keeps reverting to the one on the cloud that is wrong.

I just made a major mistake on my calendar. We keep all our appointments on our calendar and we deleted a recurring event and it deleted that 3:00 spot over all our years. I do have my calendar saved on a memory stick, however, every time I change the calendar to the memory stick, it just reverts back to what is on icloud. I have two computers linked to iCloud but need to change them both to what is on the memory stick. I'm not sure how to do that.