I’ll second the question: “What kinds of things do you want to be able to fix?” There are so many classes of repairs: electrical appliances, for which there are books, or wiring - read the code and don’t try anything dangerous, small gadgets, power adapters, and so on, but most things are on complex circuit boards with hard to identify parts, often custom chips, and many are encapsulated.

Old TV repairmen could swap tubes and look for charred parts, but when transistors and I.C.’s took over, you basically swapped out whole boards.

Other than simple things, a lot of stuff is black box in nature.

As an example, I had a Breville oven quit on me. There was an inline fuse (looks like a resistor) Simple. But I had to take out some 30 screws, and then I couldn’t find the part inside the cramped the case. So, even dead simple can be hard. A tension switch in my drier is obviously at fault, but it’s in the back, which is not accessible, so the entire drum and whatevers need to be removed to access it. Computers (not all of them) and phones are designed to be unrepairable. There are sites (forgot the names) that show teardowns and offer special tools, but good luck finding info on anything smaller than an entire logic card.

There may be books on how to build and test PC’s, if that’s what you are looking for. Make Magazine is back, and you might look at sparkfun, lilypad and any number of Arduino and Raspberry Pi publications for ideas, but other than the educational value of these publications, (I learned a ton from reading Popular Electronics), nothing specific about repairs that I know of, mostly new projects.

The more specific your question, the more specific answers you’ll get. Good luck.