Only my home page is working

I have done websites before but I am totally lost. I paid to get this theme uploaded. After I created my new main menu for my tabs like the video said none of my pages work other than my home page and the other pages gives me a 404 error page not found. I reset everything from the dashboard to start fresh just incase maybe I messed up, but it didn’t do much to change what I did other than what I had put in on my home page. Need help asap!!! Thank you!!