Platforms and meshes going invisible/disappearing

The “ue-fps” is what happened to me earlier. I got back on UE to continue with a project and things were “see-though” and faded like many things had the opacity lowered. I had tried to get help but that person had no idea. We tried many things to fix it. After getting help from that person I reloaded UE and “Blank-ue” is what it looked like after it loaded. I can not select platforms that were there before. This is a third person template. I created new projects and they were okay. I opened a different project from when I very first got UE and it was fine as well. I just want to know what the hell has happened to my project

All of this is very confusing to me because I am still learning UE