Someone is using my yahoo account too send spam mail to my contact list. what should i do to stop this?

There is nobody using your account unless you gave someone your password - most of the time you have malware on your computer that is sending out the spam You need to first run a full scan for both viruses and malware. A virus scan alone is not enough. You need to use an anti-malware program like Malwarebytes which you can download for free if you don't have it After you run the scan and delete all infected files, you need to then delete your browsing history and cookies and empty your cache Then reboot your computer, and change your email password. This should stop it Inform all of your friends that your account was hacked and not to click on any links in your emails. If they click on any links, it will infect their computer and all of their contacts will be spammed from their account