1) A strong enough electromagnetic pulse could wipe out sensitive unshielded electronics worldwide.
So, worldwide EMPs on a regular basis would accomplish the ends you are after, if you're willing to handwave a little.
For a start, all power generation could be blown, and long-distance power-lines could fry.
Also, all electronics in factories that created chips and electronics would be wiped out and would need to be retooled. Those factories typically take billions to make... assuming the knowledge is available. But with all knowledge on computers, pow, you're back to the days of books. If you're in a world where books had been completely superseded, then most knowledge on superconductor manufacture is in the heads of those engineers still alive, and in whatever electronics and storage media that happened to be shielded at the time, and some of the stuff that was turned off.
Most hard drives are pretty well shielded, but you can handwave that since the interface boards are not, and if all drives are solid-state by then, then everything gets wiped.
Rebuilding to a state where you could create complex computers in heavy shielding would take time: decades, perhaps. It's taken us less than a hundred years to get this far, and we'd already have a base of expertise to carry us this time, as well as infrastructure, so I'd estimate perhaps 40 years until we were back where we were.
Given the devastation and crash, people would be reluctant to trust computers again, and there may be laws or cultural mores against creating them, or at least in putting too much trust in them. So that could slow the recovery.
This is true however you perform your destruction of computing.
If you just affect silicon, you'd just cause some other semiconductor to be used, Ga, GaAs, GaN, AlGaAs, InP, etc.
If you affect semiconductors in general (band gap, etc), you'd just cause people to switch to some other form of femto-switching.
Either way, space travel would be the last thing people would worry about or fund, because of the greater challenges closer to home.
2) Oh, here's an approach that could work. The Singularity happens, the internet becomes an AI, and to prevent any competing AI from evolving, it immediately annexes all semiconductor plants and bans anyone from having or using electronics (enforcing its demands by its control of the world's' nukes). So you have a highly technological AI interested purely in self-preservation, migrating all computers in the world to safe bunkers in each country, removing humans except for maintenance and data entry, etc.
The rest of humanity is back to the 1800s, and re-adopts the fashion of wearing top hats and riding dirigibles.
[Edit: Neither regular, powerful EMP pulses not a Singularity are technically a change to the basic laws of physics per se, and I can think of no such change that would accomplish this. In fact, any change to the basic laws would have such far-reaching effects that the mere loss of computers would be a triviality. Like asking "how can I eliminate the use of the word 'like', just by changing some basic laws of communication?", there is no change you could make at the basic level that would affect something as exceptionally specific, without also utterly destroying the language as we know it. Changing physics as we know it would have such deep and far-reaching implications that I don't think any author could even begin to describe its effects even slightly realistically. This is definitely sledgehammer-nut territory.
Not only that, but while you can kill semiconducting digital computers, the idea of computation can't be switched off merely by altering physics, any more than a change to physics could get people to give up on transport that uses wheels, or combat that uses blades. Even if you could find a way to prevent wheels, knives and semiconductors from working, people would just invent something essentially similar: tracked vehicles, spinning sawblades, nanotech gearing systems. You can't put the computation genie back in the bottle using only a change to physics.
Instead, you need a social lever for the change of physics to push on, to discourage people from approaching (or trusting) the digital technology any further, and those social levers are the things I've tried to explore in my suggestions.]