To find .NET Framework versions by viewing the registry (.NET Framework 1-4)
1. On the Start menu, choose Run.
2. In the Open box, enter regedit.exe.
3. In the Registry Editor, open the following subkey:
HKEY_LOCAL_MACHINESOFTWAREMicrosoftNET Framework SetupNDP
To find .NET Framework versions by viewing the registry (.NET Framework 4.5 and later)
1. On the Start menu, choose Run.
2. In the Open box, enter regedit.exe.
3. In the Registry Editor, open the following subkey:
HKEY_LOCAL_MACHINESOFTWAREMicrosoftNET Framework SetupNDPv4Full
https://msdn.microsoft.com/en-us/library/hh925568(v=vs.110).aspx#net_a