Ctrangely "clipped" output in certain apps (terminals, both default and urxvt) and filemanager.
 

This is pretty difficult to explain so I've included a couple of images:

https://ibb.co/jhDth2J
https://ibb.co/58tFgXh

I'd have loved to include the output of "uname" and "dmesg" but even routing the data to a file gives me the same mess. If not entirely garbage then enough bunk to be of no use.

This began seemingly out of the blue. I am at a complete loss to explain, let alone solve, this. The keyboard works (I can use Firefox just fine obviously) and I can type commands into the terminal and they execute just fine, but as you can see I can't see what I type or the output from commands.

Anyone with an idea on what's going on here? I suspect I might have to reinstall the whole thing. :(

I have seen GPU driver quirks affect font rendering like this.
Troubleshoot that, maybe try booting in safe graphics mode, or with nomodeset etc.
Also, tell us more about your system (hard and soft).

Yes, that makes so much sense! Although I have no dedicated GPU in this laptop I've been fiddling around with C++ and OpenGL trying to get to grips with the API (You might reasonably ask why i didn't make this connection myself but I've fiddled with a lot of stuff!). I haven't really been setting any versions or modes though but I'm sure I effed something up! You're almost definitely on to something here. I was just confused as the symptoms - as I mentioned - only show up in certain apps.

At least this gives me hope that i wont have to reinstall the entire OS.

Thank you. I'll post the solution if I manage to fix it.

Regards.

Yes you do, otherwise you wouldn't be able to see anything.
Often integrated into the CPU (intel), but it's a GPU nevertheless.

If you provide some more info & initial troubleshooting results we can help you.

Ofcourse I have a graphics card. What I meant was that this is a laptop and the current graphics card is what it was "born" with. I haven't invested in any HW update. Doesn't matter though. I've reinstalled Linux and now it all works again.

I suspect the real problem was me uncritically installing packages in order to make OpenGL development work. Although I made that work I might have broken something in the process.

But the point is moot now. I thank you for your time. :)