How I resolved the issue of nothing happening when you double click on the Forge Installer .jar file.
You can also create a .bat file to run this command if you anticipate doing it more than once.
Remember to use the name of your installer file as this will change as new versions are released.
java -jar forge-1.15.2-31.2.5-installer.jar
UNABLE TO ACCESS JAR FILE - SUGGESTIONS
Make sure you are running powershell from the same location as the file is saved, and ensure you include the .jar extension in the command. If this does not work, trying moving the file out of the downloads folder to another folder that is not Documents, Downloads or the Desktop and running the command from there. Sometimes those folders have issues, although I am not sure why (might be related to Admin rights).
