Can i regain administrative permission after being hacked?

So i am reaching out about a hacking incident that occurred approximately two months ago or possibly even longer, dont really remember. Since then, I have been unable to regain control of my computer and have faced severe restrictions on its functionality.

The hacker appears to have obtained administrative permissions, thereby blocking numerous critical features and rendering me unable to perform basic tasks. I am currently unable to download files, update my Windows operating system, access my drives, enter safe mode, and encounter several other roadblocks, etc.

I am writing this in hope that someone can provide guidance or advice on potential solutions to restore control and secure my compromised system. Is there any chance that I can regain access and rectify the issues caused by the hacker?

Let me know if you require any additional information to better understand the situation or suggest potential remedies.