Hey Dionicity,
Let's try a couple of troubleshooting steps to figure this out.
First, make sure you are trying to open the Fabric installer and not the Fabric API. The API will do nothing when you try to run it directly.
Next, open a terminal or command prompt, type the following command, and share the output here.
java -version
This will help to confirm that you have the right version of Java installed and that it's set up correctly.
Then, try to open the Fabric installer from the terminal and again share the output here. The command is:
java -jar "C:\example\installer.jar"
(where you have to replace C:\example\installer.jar
with the actual path to your Fabric installer).
This method of running the installer will show a detailed error message if something is preventing the installer from working, which we can then use to troubleshoot further.