Fix and update old wordpress website

Hi, i have this wordpress website: [login to view URL] It was made in 2013-2014, and it was never updated. I just installed it again but I have the following problems: 1. The login area should automatically hide itself, but currently it does not. Does not allow access with administrator credentials. I think it must be a code conflict that makes the other functions that I will detail below not work. 2. The likes and dislikes and favorite and non-favorite buttons of the "profiles, teams and home" pages when clicked record the user's selection and store it to generate the "statistics" page boxes, when the button is clicked button should change and be marked selected, currently it doesn't work (Probably because of the code conflict in point 1). 23. Just below those two buttons I need you to add an additional button that says "View Profile" and takes you to the team or profile page. 3. Fix the slider of the home page, it dont work now. 4. Fix the buttons to share the news, I tried to share but the plugin does not work. 5. The subprovince filter should work, there are subprovinces configured for each province and each profile or team is assigned to one, I think it's a code conflict problem. 6. User registration is not working, probably a code conflict. The additional fields of the record serve so that the statistics are displayed based on those fields. 7. The news tabs don't work neither on the home page nor on the news page. Probably the same code conflict error. 8. I don't have access to the backend, I probably changed the link. I only have the username and password, I want you to tell me how to enter the backend (I don't remember if it can be entered directly from the homepage login). 9. I want you to make my menu a sticky menu and make it responsive. I think this was already done but because of the code conflict it's not working.