linux - ubuntu忘记管理员账户密码

Question

安装时的密码忘记了.....
现在只有一个来宾账户。
搜索了一下..几乎都是关于 recovery mode 的。但我的grub菜单没有显示，进不了recovery mode。
据说显示grub菜单要改 /etc/default/grub，但我没有权限！

Answer 1

Why is the grub menu not displayed? This won't happen during normal installation, please describe it clearly.
The method you can try is to enter the startup screen and press ESC, or press e to edit during the grub stage, add a single parameter or something, or use the installation disk to repair it.

Answer 2

In 14.04, if grub only searches one system, grub will not display it by default. I just pressed esc last time to get it out (it may be different for me, the keys are all different)

After seeing grub, just enter rescue mode directly without modifying grub

Answer 3

Try:
Start the machine through the previous installation CD or USB flash drive, enter the system installed on the machine through chroot, and then passwd