I have a laptop. Model name Ideapad flex 5 14ALC7. I installed Elementary OS on it. It worked fine for a while. Now it shows the screen when booting and does nothing else. I literally don't know any more.

what is the boot device

I don't know what you mean. It's booting from it's hard disk I guess? Idk what you want to know

what is the boot loader (and version)

Idk what that is, how do I find it out without being able to boot?

There could be any number of things that stop the boot, including a corrupt boot file.

Yes that is what I'm trying to find out. What thing it is. But I have no idea how. And you're just telling me that I'm unwilling for some reason.

No one is able to diagnose your problem from the information you have provided.

How am I supposed to know that? If more information is needed, I can provide that. But how am I supposed to know which information is needed?

If you are unwilling to grab a USB stick from a retailer, boot a different OS image and try some diags on your original file system

How do I do that? How would I even know that is something I have to do? Where can I find a shop that sells a USB stick with a different OS image? I guess I can find a USB stick, yes, but how do I get an OS image on it? As I said, I'm travelling and just want to use my PC. This kind of stuff didn't happen with any other operating system and I just wondered if it's possible to fix it.