Reinstall Unity Properly without Losing all my projects?

How do i reinstall unity without losing projects/projects settings, assets and files???

You can rar them? If unity sees an unity object such as a scene it automatically takes the main asset folder as a new project. So you can rar all your stuff, reinstall unity, then un-rar your stuff.

Backup your projects. Just, you know, copy them to somewhere else. The whole folder, not just the contents.