I install antivirus on my laptop but is not working

Your antivirus may not work under the following criteria
1. If you had installed two antivirus into your PC
2. If the antivirus which you have installed have few features
3. Your PC have viruses or spyware that interprets the installation or working of antivirus
Solution:
1. If it is because already installed antivirus you should un-install the previous one and reinstall the new one
2. If it is because of the second reason, you should go for some other best antivirus such as Comodo Antivirus.
3. If it is because of the third reason you should scan you pc with online tool and remove all the viruses and malware, then start up your re-installation process.

Well, which antivirus you've installed. Make sure you dont have any other antivirus installed. Because two antivirus cant work together.

Uninstall the currently installed antivirus and do a fresh install of antivirus