1. The monitor doesn't turn on.
Check VGA cable and power cord.
2. The mouse doesn't respond.
Check mouse cable and mouse’s driver.
3. No sound can when using the headphones.
Check headphone’s cable and jack and turn up its volume.
4. The computer is "frozen" (does not respond to anything).
Wait, if it still frozen for long time, restart with power button.
5. You try to connect to the internet but only your computer does not connect, other computers in the room work well.
Check LAN cable for LAN or check your computer’s Wi-Fi signal for Wi-Fi.