How can I change the password? I can not enter the computer. asks a user password? How can I find it.

Answer 1, Authority 100%

Regarding the title of the question: In Ubunt, the login on behalf of the ROOT user is prohibited, and he does not have a password. Use the Sudo command and enter your password. The user, respectively, should have privileges (see /etc/sudoers).link

Answer 2, Authority 67%

in no way.

You can only reset to a new in the presence of physical access to the car – http://habrahabr.ru/post/54103/

Answer 3, Authority 67%

Find out the password just will not work, but it can be reset, install it
new. There are a few simple ways to do.

download to single-user mode

If a GRUB without a password is used on the desired machine as a loader,
Such actions are suitable.

1. turn on the computer and wait for the OS selection screen (if the selection does not appear,
   You need to press the ESC key at the time of download).
2. as soon as you managed to get into the bootloader menu, Mouse over to the desired
   System and press the E key. You will get into a simple editor for
   of this item.
3. Locate the line starting with Linux , and add a word to the end
   Single .
4. boot with modified settings by pressing F10 .
5. after a while you will fall into the privileged mode. Type
   Team Passwd User and set the password of the specified user
   Systems.
6. Then enter the exit command, and the download will continue as usual. But password
   will already be replaced.

Substitution Demon Initialization

Single-user loading mode can be blocked *. In this case
You can try to replace the path to the program of initial initialization.

1. for this at the stage of editing the settings of the item in the loader (see №3
   Above), instead of the Single parameter write init = / bin / bash .

2. booting (key>f10 ), you need to mount the root section
   To write.

   Mount -W -o Remount /
   

3. Then similarly change the password utility passwd .

4. and then restart the computer by the reboot -f command. Password will
   Changed.

^{* in SystemD This is done by masking the unit Rescue.Target .}

Loading with Live Image

Administrator may prohibit changing download parameters, putting a password on
Grub . This will complicate previous items, and have to resort to help.
installation flash drive.

1. By downloading the Live system from a flash drive (or in an old-fashioned CD), in the terminal
   Montore the system section of the target OS. You can find it with utilities
   fdisk or gparted .

   sudo mount / dev / sdan / mnt
   

2. then change the root directory

   sudo chroot / mnt / bin / bash
   

3. Change the password as well as in previous versions of the program Passwd .

4. and restart the computer with a changed password.

As a counteraction, this option is invited to put a password and on
BIOS and hang the lock on the body or seal it.

Editing User Database

In the previous case, to pass the focus with the replacement of the root, the experimental system and
The system from the flash drive must be architectically compatible. If it is not, you can
Edit file / etc / passwd Target OS.

1. Open Passwd file that contains a list of users in any
   text editor (or even in any OS, in which there is support for Linux
   FS).

2. Find the desired user (names in the first column to the colon) and
   Remove any characters up to the second colon in the string. This will lose
   User password on empty.

   Example: The file was

   root: x: 0: 0: root: / root: / bin / bash
   

   should get

   root :: 0: 0: root: / root: / bin / bash
   

3. By booting into the target system, it is advisable to re-install the password.

but in fact, that truly protect the data from unauthorized
Access, they should be encrypted. In this case, you can be sure that
The foregoing instructions will not fit. And if you suddenly forgot your password from
Kryptokontainer, the simplest solution is to forget about it. However, this is not
Theme of this Answer.

Answer 4, Authority 33%

In the buckunt, you can go from the root through the recovery mode