Wearable computers are nice, and some are designed to be fairly durable. Most are not, however, and repeated flexing, washing, or wear will crack or bend internal components. High end versions had removable memory cartridges that act as a back-ups, but most were meant for closet interfaces or wi-fi. Cell-phones and tablets also tended to have a problem with durability - so long as circuits are printed or soldered together, there is a way for them to separate. Crystal disks are an exception, since its all arrayed in the matrix, thus data taking physical form in the block - but you still need something to read that disk.
So the search is on for actual computers, and that is always a bit of a pain. Computers became a part of everyday life quite literally - you computer desk was not a piece of wood you put a CPU on top of, but contained the processor itself. Testing tables in ruins and then dragging out the complete object is an annoying job for movers under good circumstances, much less when reanimates or aliens are about. Stand alone computers still exist, but are more of a specialists tool or gamer's toy.
You could hack something out of multiple game stations and some code - but how many of us are actually engineers versus casual end users? Still easier than working with a computer of Citizen design. The basics are the same, but their code is either undocumented, or the comments are written in the offspring of Braille and musical notation. Someone has probably opened their OSes, but they aren't selling, so what good is it?
Basements are the key. Hospitals, government buildings, factories - those sites have usually been exploited or destroyed. The average attic full of junk might still be useful however. Never underestimate the little scores of suburbia.