If your computer has no lights, no fans, or a black screen (power-on self-test failure): Start with a hard reset.
If your computer is acting up, don't panic! Most issues can be resolved with some simple troubleshooting. Phase 1: The "No POST" / Won't Turn On Panic computer trouble shooting
If your fan is running loud or the computer shuts down randomly: If your computer has no lights, no fans,
(e.g., black screen, blue screen, loud fan, frozen) Are you seeing any error codes or hearing beeps? Is this a laptop or desktop? If your computer has no lights