Technology is any device or knowledge which helps a person do work. Technology is both possible because and is limited by the laws of physics. Things like thermodynamics, mechanics, statics, and others. In a more concrete way, technology is limited by the energy a society has at its disposal and the materials a society has at its disposal.
After the crash, many materials and energy sources will become unavailable to us. There will be little or no oil and precious little coal. There will certainly not be a sufficient amount of fossil fuels available for industrialization. But industry is a technology, not a synonym for technology. Before industry clever craftsmen invented steel, blades sharp enough to cut through paper floating in a breeze, glass, ceramics, telescopes, printing presses, and a million other things. None of which required fossil fuels.
It was recently my privilege to watch and participate in an activity that has been called impossible by other sources. Using nothing but salvage and rusted iron, myself and others made high-carbon iron knives. The forge was made from pieces of an old car. The bellows were made from an old heavy-duty trash bag. And the fuel was charcoal. After the crash there will be an ample supply of old cars. Plastic trash bags are essentially immortal, and could be replaced easily enough. And charcoal is made every time you set a camp fire. Higher quality charcoal can be made by letting large quantities of wood smolder for a few days, but this is not a difficult process. This forge, and other related technologies, will give us iron, and possibly even steel. Copper could be completely melted at these temperatures.
Glass is also very simple to make. It requires a heat source and sand. Certain sands make better glass, but any sand will do. Glass itself is more useful than many might believe. First, it is one of the most basic materials required to make solar-powered devices. If it is passive solar, it can be the only item. Second, with glass manufacture, a craftsman could make optical lenses. Optical lenses would not only allow people to see who would otherwise be blind, but also permit things like the magnification of sunlight or an approaching army. With a little more experimentation, metal working and glass manufacture could allow a society to have solar panels, the kind that generate electricity.
Beyond this we often underestimate the most basic materials. Using only wood, a clever person could easily make a waterwheel. With that waterwheel and copper wiring, perhaps harvested from millions of miles of unused power lines, a water wheel can generate electricity.
Technological development will not vanish after the crash. It will change. This change will probably mean that some areas of development will be slowed and perhaps completely neglected. For instance, without such a readily available source of hydro-carbons, rockets will probably become only a memory. But creating a huge explosion is hardly the only, and far from the most efficient, way of propelling a vehicle. It might even be possible, given time, ingenuity, and motivation, for humans to conquer space, post-crash. Computers are also not out of the question. They might not be as small and fast as some current versions, but they are not out of the realm of possibility.
And all of this ignores what is perhaps the most intriguing possibility. Perhaps spending so much time on electricity has limited our vision. Only quite recently have we even begun to really explore the possibilities of light. We now have both fiber optics (made from glass among other things) and crystalline semi-conductors of light. This means that we are very close to the first optical computer. A computer that runs on photons rather than electrons opens many possibilities. While we may run out of fossil fuels to burn for electricity, we will not run out of light until the world itself is long dead.
All of this is very speculative, but none of it is out of the question. Many of the points in this article were simplified for the purposes of length. If anyone would like to discuss details or argue the point, please feel free to comment. (Note: I am aware that fiber optics also require synthetic polymers that would tend to be unavailable post-crash, humor me and wonder for a few minutes.)