I have downloaded unity and when I open it, I can’t see any instruments (all interface). I can see only scene with camera. The screenshot is below. Please help 
try installing an older version of unity, guessing that the version you downloaded is still in beta and the fact that you seem to have an older operating system of Windows, it could be a bug. Or reinstall that version of Unity, but if it still doesn’t work, you may need to report it.
You can also try to click on window and then enable all windows you need. And if it’s still not working, then reinstall Unity as NoCandyIncluded already said.