i did absolutely nothing to 3 blogs (2 in subfolders and 1 in a main url folder). The 2 blogs in the subfolder - all of the post links stopped working out of nowhere. The 1 blog in the main folder is fine. Someone from your company looked into it, playing with all the plugins & updating wp. Nothing worked. They changed the url names to something custom, but with all url names changed I lose the inbound links. I need this fixed or it is a serious problem for SEO, which btw is how the business stays open.