HELP: Booting problems, caused by grub config changing maybe..
 

Hello, i am new user to ubuntu bcs i want to migrate from windows, i like to set up my pc by looking tutorials and articles. i'm not a pro user, but i understand how to use terminal, installing programs,
and until yesterday, I installed many program for my daily using, but that time, maybe i accidentally changed the grub config. So i tried to look tutorials and solved the first problem, but I'm too obsessed haha, and then i changed the grub config again, and after i tried to reboot...
1. system bootorder not found. initializing default
creating boot entry "Boot000A"with label "ubuntu" for file "EFI\ubuntu\shimx64.efi' and then...
2. error: can't find command 'hmwatch'.
system bootorder not found. initializing default
3. error: no such device: F515-593E
error: out of memory
press any key to continue...

failed to boot both default and failback entries.

4. and the last one, the biggest nightmare i've ever had, maybe....
sooooo many abstract characters came out, oh my goodness that was so scary:"

and then it went to grub2, and there were like 3 or 4 choices, like ubuntu, advanced setting for ubuntu, system setting (BIOS), etc i forgot.
i can't figure it out what really happens to my laptop, and until now i haven't found any helpful articles or yt video tutorials that work for me.
idk how to fix it, and rarely people around me using linux. and i haven't backup my data huhu, but i think it won't be deleted, hope so. i can't reinstall ubuntu for now, since i haven't backup my data.
I hope that you guys can help me, big love from Indonesia!! <3 <3 thank you so much (sorry for my bad english, not a native hehe)

Probably easiest to re-install grub completely. Here is a page that refers to "Grub 2", but these days it is known simply as "grub". If you click the included link to grub-repair, there are details on how to get and run it.
That should solve your problems.

In future don't mess with your boot-loader.

Thank you so much, i'll try it later.

oh, one question. we can run boot repair from live cd/usb right? we i tried ubuntu live session, i can't connect to wifi, it said there's no wifi adapter. So i burn/flash boot-repair's iso file to my usb drive, then open it while running ubuntu live session? am I wrong?

No, it's a bootable liveCD that launches boot-repair automatically. Just burn it and boot it.

Thank you, is this option will erase all my data on my 'broken' ubuntu? If that's so, it's okay than I can't use my laptop forever.

No, it won't do any more than output information. You download it and put it on a CD or USB, boot from that CD or USB and run boot repair which should have an option to Create BootInfo Summary. Select that and you should get a link at the end to post here which will provide information. Explained in detail at the link below. That information is needed for anyone to make a realistic suggestion on a solution.

https://help.ubuntu.com/community/Boot-Repair