Stuck on a problem for months because i forget the password

Good day

I was trying to install Slackware but I have a problem, when I was set up the user root and the visual interfaz I forget the password therefore I try to fix in other ways that I dont remeber good, the problem is this, I turn on the computer and the first screen is this:

GNU GRUB Version 2.06
grub>

I figured that I can boot into the system if I run this comands:

insmod all_video
set root=(hd0,gpt3);
linux /boot/vmlinuz root=/dev/sda1 nomodeset
initrd /boot/initrd.gz;
boot

After that, the screen show me this:

modprobe: ERROR: could not insert iext4: Exec format error
mount: mounting /dev/sda1 on /mnt failed: Invalid argument.
ERROR: No /sbin/init found on rootdev (or not mounted). Trouble ahead.
You can try to fix it. Type iexiti when things are done.

/bin/sh: cant acces tty: job control turned off
/#

Thing that I know:

This envioremen the system is not monted in rewrite
The problem is not in init command
The problem is at the grub boatloader

I try to restore the factory settings but was useless, do you have any idea what can I do?

Thank you beforehand