The iTunes store may fail to work due to a firewall, viruses, incomplete or poor installation or conflicts with other non-Apple programs or plug-ins. When not in its latest version, iTunes may also experience problems interacting with updated devices.
If iTunes doesn’t even start running, the computer's firewall or its processes may already be in use. If it starts but doesn’t react, the issue might be anything from poor Internet connection to damaged configuration files.
Go to Settings and allow the iTunes program to run through the firewall. If firewall access is not the issue, restart iTunes after clicking “end process” in Task Manager. Running the iTunes setup file and following the wizard prompts might also be able to solve the problem. If all these efforts fail, a complete reinstallation of the iTunes software might be the best remedy and ensure the version reinstalled is up to date.
Proxy settings can also cause a malfunction. Go to the browser’s network settings, head to “Lan Settings” and ensure the proxy setting is not checked. Also update antivirus software to check for viruses but exclude the software from scanning iTunes, because in some instances, antivirus software causes the program to force-quit itself.