Computers occasionally experience hardware problems. The older the computer is, the more likely some component will fail sooner or later.
Various types of hardware failure are possible. By far, the most common hardware failure is a bad hard drive. Hard drives are one of the few parts of your computer that have physical movement. Hard drives spin a magnetic disk thousands of times per minute while you use your computer. Because of the physical wear over time, they are the most likely component to fail. They typically last several years, but they are bound to fail eventually. That is why we recommend everybody has a backup solution in place so they don't lose their data.
The symptoms of hard drive failure are usually pretty obvious. Often, once a hard drive failure has occurred, a computer will be unable to start up properly anymore. If one day your computer works fine, and the next day it fails to startup, the hard drive is a likely culprit. The other common symptom of hard drive failure is your computer being slow. As in, slow to the point of being unusable. For example, it may be that programs don't open anymore, or take minutes to open.
There are other possible hardware failures as well. Some computers work fine, but shutdown after a few minutes, or shutdown once you start running a certain program. This is sometimes caused by overheating. When the computer detects it has gotten too warm, it will shut down to prevent heat damage. Overheating problems can typically be remedied by blowing dust out of the computer or reapplying thermal paste on the CPU. Replacing fans is also an option, especially if a fan stopped working.
Motherboard failure also happens in rare instances. If a motherboard failure has occurred, the computer will not start up at all. These problems are often caused by a power surge during a storm or similar electrical events. Fortunately, replacing the motherboard is possible.
There are also a few problems specific to laptops, such as missing keycaps on a keyboard or a broken screen.