Firstly, in order to fix the connection issue, check your Internet connection. If you're able to connect to Internet, navigate to Start > Control Panel > System and Security > Windows Firewall > Allow a program through Windows Firewall and check the box next to Hotspot Shield. If you can't find the application in the Allowed programs and features window, press the Allow another program button, navigate to the installation directory, select the executable file and press Add.
After that, from the Advanced Settings select Inbound Rules > New Rule. Check the Port box, click Next, select All local Ports and follow the self-explained steps. Also, make sure that your security program doesn't block the connection.
If you still have issues, remove the software (Control panel > Uninstall a program), run a registry cleaner from Software Informer database and download and install its latest version. If the connection problem persists, its possible that the Hotspot Shield servers to be temporarily down or under maintenance. In this case you will need to wait. I suggest you contact the Support team for further information.