If you're having trouble using weapons in Fortnite, there are a few things you can try to fix the issue. First, make sure that you have the latest version of the game installed. If you're still having trouble, try restarting your device. If neither of those solutions work, it's possible that there's an issue with your account or console. You can check for any known issues on the Fortnite status page, or contact customer support for help.