Horizon won't open

When I start Horizon, the logo appears on the screen for about a second, and then disappears. I’ve tried uninstalling and reinstalling it, and tried reinstalling my .net framework. I have Windows 10.

Do you have .Net Framework 3.5? Horizon will not run without it.

Get it here: https://www.microsoft.com/en-us/download/details.aspx?id=25150