I would say the answer to fixing computers is learning to replace the hard drive and learning how to backup or recover data.
This is why it's important to learn hard drive replacement. Most of the faults on computers will be directly or indirectly related to the hard drive.
For example, a virus infection is a harmful program which may or may not damage data on the hard drive. Defects on the disk make the hard drive life difficult and eventually the hard drive fails to read certain disk parts. It's important to know how to get data from the hard drive and how to make it work or how to replace it.
There is little difference between desktop and laptop hard drives. Depending on the system age, a different interface, SATA or IDE is needed.
The second step is to learn the simple part replacement process on desktops and laptops. On laptops, this is frequently the LCD screen, hard drive, memory, and sometimes, it is needed to disassemble and clean it thoroughly and then apply heat sink paste.
Desktops also need the heat sink taken out and for heat sink paste to be reapplied sometimes.
The vast majority of video tutorials can be found on YouTube. These videos make a very good start when learning how to fix computers. The only problem there is while watching videos is that you need to know what you are looking for. For beginners, YouTube is actually not a good place to go as it can lead to bad advice through poorly described videos.
It is always advised that a good start is to read books on computer repair. A helpful book is 'Desktop and Portable Systems' which pertain to Apple products.
This book is very well-written and gives a great foundation for learning about how to fix computers. I have a colleague that has his own business in Birmingham and every time he asks me for a help I remind him to read this book, as many faults can be diagnosed just by using this book.
Of course, this site also has helpful information which is hard to find elsewhere. It is not easy to make a website about computer repair, and the book is probably easier to read. This is because, it's easy to open a book in the evening and read it without distraction.
The second step is to read books on A+ certification.
After reading these books, the only one way to truly learn is through trial and error. It is advised to get a faulty cheap laptop and a faulty cheap desktop probably and practice on it. Disassemble and assemble it, measure voltages with a multimeter, take pictures of it, ask online forums about symptoms, etc. You will be amazed as to how much good information can be found on forums. When you search for something on search engines, add a word forum and discover a world of communities. Facebook does not have good search capability, but hopefully in the future, Facebook will include something similar to Google.
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