If you want to restart your VPS, you should login to the VPS, and issue the restart command on the VPS.

In case of windows, login via remote desktop, click on Start menu, and there you can reboot the VPS/Windows.

For the other operating systems, you should login via SSH, then issue the following command:
reboot

If you cannot login to the operating system (remote desktop or SSH not available), you should check your VPS on our VPS control panel, and use the console.