Unity attached Editors does not show suggestions (No IntelliSense)

I work offline at Home developing at Unity, I open Unity after a long time when scripting it does not show suggestion while scripting in VS Code. After this problem i installed Monodevelop for fixing this issue but still no result. Now i have plan to Switch to Visual Studio 2019 Community but that still not able to install as i have questioned. So Kindly guide me about Whether to switch (install) VS 2019 or it’s ok to use monodevelop or VSCode? Which is the best in your opinions? Or I have to fix the above issue of No Suggestion in either MonoDevelop or VS Code or Install VS 2019 for that purpose only (may be it still have the problem NO IntelliSense)?

Problem Solved by Updating .Net Framwork