How can I debug why Ubuntu boots to BusyBox? [duplicate]

When I turn my PC on, it asks me if I want to boot Ubuntu 16.04 or Windows 10. When I choose Ubuntu 16.04, it look like it is booting, but then it just show me this screen:

BusyBox v1.22.1 (Ubuntu 1:1.22.0-15ubuntu1) built-in shell (ash)
Enter 'help' for a list of built-in commands

(initramfs)

I was installing Ubuntu by CD. First time, when was installation complete, the system was running without any problems, but when I turned my PC off (there wasn't any problems or messages during the shutdown) and then turned it on and choosed Ubuntu this happend.

Solution 1:

Boot from a live USB stick or DVD and run:

sudo fsck -a /dev/sda1

Important! --> replace /dev/sda1 with your Ubuntu partition.

Youo can locate the correct partition with the command lsblk which will provide you with output similar to what you see below your Ubuntu partition is the one shown at mountpoint /:

NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 119.2G  0 disk 
├─sda1   8:1    0  12.4G  0 part 
└─sda2   8:2    0 106.9G  0 part /
sdb      8:16   0   1.8T  0 disk 
└─sdb1   8:17   0   1.8T  0 part /home
sdc      8:32   0   2.7T  0 disk 
├─sdc1   8:33   0   2.7T  0 part /srv
└─sdc2   8:34   0     1G  0 part [SWAP]
sr0     11:0    1  1024M  0 rom