it's a sad day, the first time i competely fucked my computer
i tried to get kde plasma on my fedora, when i booted it up there was just a black screen. i couldn't type any commands either, it was toast
thankfully i've got windows dual booted because i'm a filthy 
who uses it for vr games. unfortunately windows doesn't let me see my linux drive's files so all of my personal files are unrecoverable.
thankfully i think the most i had on my computer was my music (yt-dlp is so easy i can get it all back in 30 minutes tops) and a few files from some project i was working on, sucks but not worth spending hours troubleshooting. oh well.
on the bright side, i'm RETVRN-ing to my old reliable, linux mint with xfce. i'll miss hot corner and the other niceties that gnome has but xfce will be a bit more comfortable for me.
Just make a bootable usb key with a live distro all your files should be easily accessible.
I second that. Always have a bootable disk ready (or even better a bootable image on your machine) so you can recover from any issues in a snap. Over the course of 20 years using Linux I can only remember two blackscreens. Unlike other OS, these situations don't happen randomly but mostly when the user mess up with the system (like in your case) and that's great opportunities to learn a lot about your system because that's when you really need to understand how it works.
You could simply switch to a virtual TTY with CTRL+ALT+ARROW KEYS
Second, you are not special because you use Linux. You are not trash because you use Windows. At the end of the day we are all just slowly moving to more open solutions like Linux because they are better.
Just a side note but you should not install two different desktops at the same time. Best practice is to do a fresh install with a clean home but you also can install KDE and remove gnome though dnf groups.
First, it's a right of passage. You should be happy.
Second - it's only a failure if you learn nothing. Spend the time, learn what you did, know better next time. That's how you learn.
There are a number of ways to access your Linux drives from Windows (I did it regularly when I ran Windows) and if your drive hasn't been wiped your data is probably all accessible. Here's a link that should help: https://www.howtogeek.com/112888/3-ways-to-access-your-linux-partitions-from-windows/
It sounds like the system booted. They probably just need to switch to a virtual teletype.
If you can boot windows, that means you can get past the bootloader, which means it's actually running linux before the screen goes black. with that in mind:
do yoy have extra kernels you can boot into? I use Debian, and they automatically maintain a few boot options including an older kernel and a "rescue mode". But that might just be debian for all i know
any change when you plug your monitor into your PC motherboard's graphics port instesd of the GPU?
can you switch between TTYs once the os boots and the screen goes black?
Sometimes graphics issues like this just means the GPU isn't working, which 2 should diagnose. But given that it happened when you tried to switch DEs, my bet is on either the Display Manager or the window server (x or wayland) failing, which 3 should get you around, and then you can proceed to diagnose and unbork it from the terminal
Can you not do something with gparted on a live usb? Or are the files that fucked?
i tried, but i guess they really are just that fucked. i have no idea what i did wrong. this is the last time i try and do something without a guide on linux, i am not smart enough for this lmao
imo the best feeling is finding out the root cause and unfucking the system when it's like this
Nice, new chance to try a new distro :)
If it's btrfs there is a windows driver for it ext4 also has one but it just doesn't work for me
Press Ctrl-alt-f2, look at the x logs.