What .NET version are you running (2.0, 4.5, 4.5.1 or 4.5.2)

From .NET 2.0 to 3.5

Right click on C:\Windows\Microsoft.NET\Framework\v2.0.50727\mscorwks.dll and choose properties
Go to Details tab and look at file version

.NET 4.0, 4.5, 4.5.1 and 4.5.2

Right click on C:\Windows\Microsoft.NET\Framework\v4.0.30319\clr.dll and choose properties
Go to Details tab and look at file version