Can't find pages on local server

Hello everyone,

I am updating a site and was working on adding jump links to anchors I had added into a page that I was working on. The problem is that randomly the server stopped being able to find the pages. I can get to the home page (localhost/sitename) but none of my navigation links work to receive the other pages. The last time this happened I had to reinstall wordpress core and that seemed to work alright. Is there an easier explanation or something I did to cause this so that I can avoid it in the future?
Thank you