Troubleshooting guides
30 guides that start from the symptom rather than the device. Each one explains what is actually happening and links to the test that confirms it.
Any device
Keyboard Test
Open the keyboard testMouse Test
Open the mouse testDead Pixel Test
Open the dead pixel testController Test
Open the controller testRefresh Rate Test
Open the refresh rate testMicrophone Test
Open the microphone testSpeaker Test
Open the speaker testWebcam Test
Open the webcam testNot sure where to start?
If you know which device is misbehaving, go straight to its test. The guides are for the cases where the symptom is clear but the cause is not, which is most of them: a mouse that double clicks might be a worn switch or a setting, and a camera that will not open is almost never broken hardware.
Every guide says which it is likely to be, and none of them assume the answer is new hardware.