Bashes head into wall...Dual Partition ubuntu/debian password issue

[QuantumParadox]

OK SO
pretty much I wanted to get rid of ubuntu, made a usb with unetbootin tried to install debian and there was something wrong with the boot loader....I then gave up tried to go back to ubuntu and when i made the usb with unetbootin and ubuntu went to install it showed debain since it had installed i just didnt have the boot loader... so i told it to partition and kept both... I can log into ubuntu but when i got to log into debian I know the user name is (95%) certain what I always use but it doesnt show you in deb what the user name is before it prompts you to put in the password.. and i always use the same password too! so i think that since there was no light and it was late i messed up when putting in the password?? and did it the same way both times?? so I tried to go into grub to reset the password but when i use the commands i found online they dont work and when i use the list given from pressing tab (password or password_pbkdf2) I get the error two arguments expected...i feel like thats because grub doesnt know what password i want to reset...when i load grub it says ubuntu 1st, then debian and at the top it says grub ubuntu---or somthing like that...

so how do i tell it to reset the debian password?????? like omg i got so excited when i saw both and i could boot both and then i do a victory lap only to discover this issue... like i want to bash my face into a wall or just toss this computer out a window! gah! PLEASSEEE SMARTIE PANTS EXPERIENCED LINUX/GRUB USERS SHOW ME THE WAY!

[yancek]

You can't reset your system (Debian) password from Grub. Read the link below which explains how to do it using a Live Ubuntu CD. You can do the same by booting into your Ubuntu system.

Reset Your Ubuntu Password Easily from the Live CD - How-To Geek

[cynwulf]

If you want to reset a password, then single user mode is what you want. Boot into that and

passwd yourusername

substitute "yourusername" with your own user name or "root" if it's the root password you're trying to change. Enter the password twice, preferably with the lights on this time, and reboot.

[devils casper]

I would suggest you to boot up Ubuntu and mount / partition of Debian. Check its /home folder. There will be folder for user that you have created during installation. After verifying username, boot up Debian in Single User Mode and execute passwd username command to reset it's password. It won't ask for earlier password.

[lugoteehalt]

If you know root's password then log on as root - give 'root' as the user name and then root's password. Then simply use the passwd command to set the user's password. If the user's name is unknown perhaps look in /etc/group for it.