Sometimes, the programs you use to connect to your PC (e.g. TeamViewer) might fail and your computer might need a reboot to start them again. If your Web server running PHP is still up and running and you have a way to create a file on it (some php file editor, ftp etc.).
This is what it needs to contain:
<?php
exec('shutdown -f -t 0 -r');
?>
More details about the shutdown command you will find below:
| Parameter | Function | 
|---|---|
| -s | Shuts down the comptuer. | 
| -r | Reboots the computer. | 
| -f | Force-close all running applications. | 
| -m \\Computer | Specifies a specific computer on the network that you want to shut down or reboot. Absent this parameter, the command affects only the local PC on which it is run. | 
| -t xx | Sets a delay (xx seconds) before the specified operation commences. | 
| -c "message" | Add your own text inside the quotations to provide remote users with a message about why and when their PC will shut down or reboot. | 
| /a | Aborts a shutdown or restart if used during the (-t) delay period. | 
| /h | Hibernates the computer. | 
| /? | Displays the full help document with all commands. | 
