hello faisal
I can understand its very frustrating to go through a problem like this. We appreciate your patience. To solve this problem we need to try other methods first thing I want you try is that remove all the credentials related to Microsoft and its services and check if it resolves your issue.
Go to control panel > search credential manager > click on manage windows credential > now search for office related files and one by one remove them all
You can refer to the article linked below for more troubleshooting steps. Its just a little advance you will need to know how to use cmd prompt because we need to remove the product key from the system which gets saved in it.
=> https://docs.microsoft.com/en-us/office/trouble...
I am also sharing a video from youtube where this commands are used so you can understand how to work with them. "remove all the office related product.
https://www.youtube.com/watch?v=pJFgT7LkLwc
Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.
Hope this resolves your issue update me with the results.
Regards
Himalay