Usually Google the error message. Or find some ElementaryOS forum and ask there. Maybe use their search function first. Other than that you could visit some friend and use their computer to prepare a new intall medium...
If you ask someone (with expertise, on the internet): Don't overly ask to ask. Volunteer all necessary information. Include the exact error message, maybe a log or screenshot. Say what lead to the situation. Give version numbers (if known).
@Azzu Usually googling error message will lead you either to stack exchange(by stack overflow) or distros forum, and if you can't find fix - just ask on both. But you would need to elaborate further on what do you see.
First up - I know nothing about your specific problem. Let me add some pointers as to why you may be having difficulty...
You need to provide way more detail than a screenshot (which shows nothing really) and "why is it broken?"
What is the hardware, what is the boot device, what is the boot loader (and version), what does the boot loader config look like... There could be any number of things that stop the boot, including a corrupt boot file.
No one is able to diagnose your problem from the information you have provided.
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 you may well find people reluctant to help (for free...)
You are right, it doesn't happen with any other O/S except iOS where you have to pay people/Apple to fix it (or reset the OS) or Windows where the stock response is "reinstall the O/S"
How valuable is the data on your laptop? Did you have it backed up? If so, stop worrying and just take the Windows approach. If not... Find someone local to you who is able to fix it (good luck with that...)
As for the rest - you come over as someone who expects someone else to fix your shit for free with no information other than "waaaa it's stopped working"
Fwiw, based on your brief description of symptoms, I would say your boot device file system is broken somehow. To fix you need to mount it on another booted OS and fsck it (however if it mounts, copy valuable data off onto other media, then fsck it) . How to do that is left to your powers of Google. Not warranting my response in any way.
You seem very fixed in your opinion that I'm some sort of crybaby. You must remember that there are people that have less knowledge than you have. I installed Linux because of people here suggesting it, with exactly the amount of knowledge you would have if you never bothered with operating systems before, so, none.
There have been problems with it. First I had to fix the system staying black after waking up from sleep. Then the webcam stopped working. Now it doesn't even boot anymore.
expects someone else to fix your shit for free
Actually, not at all. I looked for paid support options as well, but didn't find any that looked reputable.
How valuable is the data on your laptop? Did you have it backed up? If so, stop worrying and just take the Windows approach.
Not extremely, however it's extremely surprising that you would suggest me to use Windows. I'm as unfamiliar with it as Linux.
This may help How to as Smart Questions
Look at my original question. I'm literally trying to find out information like the one you posted in this guide. Thank you for offering that, but there really was no need to be condescending about me together with it, accusing me of being lazy. I tried to figure it out, but I just have no knowledge to even search effectively.
To fix you need to mount it on another booted OS...
Thanks but that was the problem, I'm travelling and don't know where to get another OS to boot to from.