I've always used visual studio and never had problems. I have the community version 2017 installed, and I was using it normally, but I had to pause the development I was doing. Now that I came back (about 2 months later), an update came out and I installed it without problems. The problem comes now:
Visual studio is no longer suggesting auto-completes of classes, nor even imports / using. It works just like a notepad ++, it only changes the color of things. When I try to compile, it triggers a lot of errors "missing import", "undeclared variable", all because it is not making any suggestions.
I wanted to help you to solve this problem (I have already repaired it in Visual Studio Installer, but it did not work).