INFORMATICS

Use PowerShell to Detect .NET Versions

gci ‘HKLM:\SOFTWARE\Microsoft\NET Framework Setup\NDP’ -recurse | gp -name Version -EA 0 | where { $_.PSChildName -match ‘^(?!S)\p{L}’} | select PSChildName, Version

manual way of checking

is to look in the folders where most of the .NET program files are stored to see what’s in there. The location is in the C:\Windows\Microsoft.NET\Framework folder and also the Framework64 folder for 64-bit systems
Read More: https://www.raymond.cc/blog/how-to-check-what-version-of-microsoft-net-framework-is-installed-in-computer/2/

Find .NET Framework version from command prompt

wmic product get description | findstr /C:.NET

or 
You can check the version of .NET Framework installed on a computer by opening a command prompt, 
navigating to \%windir%\Microsoft.NET\FrameWork, and then navigating to the directory with the latest version number. 
Once in the directory with the latest version number, run the command .\MSBuild.exe -version

You can list older .NET versions running on your computer by running a simple command shown below.

dir  /b  %windir%\Microsoft.NET\Framework\v*

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Using the following table, you can establish a correspondence between the release number and the version of the .NET Framework 4.5.