If it's not malware, there could be several other possible causes for the strange sounds and broken mouse. Here are a few things you can try to troubleshoot the issue:
1. Check for recently installed programs or updates: If your friends made any changes to your system, it's possible that they installed a program or made changes that are causing the strange sounds and mouse issues. Check the list of recently installed programs or updates and try uninstalling any suspicious ones.
2. Update drivers: Outdated or incompatible drivers can sometimes cause unusual behavior. Try updating the drivers for your sound card and mouse by visiting the manufacturer's website and downloading the latest versions.
3. Check system sound settings: It's possible that your friends may have changed the sound settings on your computer. Go to the sound settings in the control panel and make sure everything is configured correctly.
4. Restore system to a previous point: If none of the above solutions work, you can try using the system restore feature to roll back your computer to a previous point in time when everything was working properly. This will undo any changes made by your friends.
If none of these solutions resolve the issues, it may be worth seeking assistance from a professional technician or posting more detailed information about the problem in a tech support community.