Determining the failure of your hard drive is not always straightforward. Some types of failures are obvious to detect and others not. Some very common signs that your hard drive is failing are:

Loud Noises: If your drive makes unusual noises such as clicking, grinding, scraping or emitting a very high-pitched whine, then this is a clear indication that your drive is either soon failing or has already failed.

Not recognised: If your hard drive is not recognised at all in BIOS during boot time, while it used to in the past, that is also and indication of some sort of hard drive failure.

Smart Indication: If your hard drive supports the Self-Monitoring, Analysis and Reporting Technology (SMART), then any indication of a SMART error while booting your computer is a clear sign that your hard drive is failing.