Laptop won't boot to either Ubuntu or Windows

I have an HP laptop with dual OS - Windows 10 and Ubuntu 18.4.

Yesterday when I booted into windows, it wouldn't go past the 'blue screen', it shows -

" your pc/ device needs to be repaired."

The Operating system couldn't be loaded because the system registry file is missing or contains errors.

File: \ windows\system32\config\system

Error code: 0Xc00000e9

I tried many methods from the internet with no luck. But I still had access to all my files since Ubuntu booted fine.

Then, following an instruction from reddit, I downloaded mini Windows 10 iso from my Ubuntu. I was formatting my USB when the lockscreen showed up. It was glitchy and wouldn't let me type my password. So I turned off the power button and rebooted. But it showed a black screen saying /dev/sda5 contained errors and to run fsck manually. With my USB still inserted, I ran fsck. Answered yes to all the questions. And finally after successful fsck, I typed exit. But then it showed an error that roughly said,

run-init: /sbin/init: No such file or directory Kernel panic - not syncing: Attempted to kill init!

Rebooted a few times, still says the same. Tried booting into recovery mode. Again, says the same.

So now I have two OS that won't boot. All my files are in the laptop. I don't have an installation cd or media with an iso file. The only thing I can see is the GRUB menu and the terminal from there. What do I do?