1) Please see if this helps: Boot drops to a (initramfs) prompts/busybox
On link from above post says:Initramfs Prompt When Ubuntu Boots : This can occur when you have installed Ubuntu on an NTFS Windows partition and Windows was incorrectly shutdown.
Solution:
(initramfs)exit
You may get something like this —
/dev/sda1: Unexpected …
fsck exited ….
The root filesystem on /dev/sda1 requires manual fsck
BusyBox v1.22 ……
(initramfs)
… means etc etc.
Now use the following command
(initramfs)fsck /dev/sda1
(pl note that /dev/ is constant. sda1 is to be known from the line above — The root filesystem on /dev/sda1 requires manual fsck)
Here change sda1 with your
2) Another post Ubuntu 16.04/17.10 Boots to Initramfs
suggest this solution:
To check the file system on your Ubuntu partition...
boot to the GRUB menu
choose Advanced Options
choose Recovery mode
choose Root access
at the # prompt, type sudo fsck -f /
repeat the fsck command if there were errors
type reboot
If for some reason you can't do the above...
boot to a Ubuntu Live DVD/USB
start gparted and determine which /dev/sdaX is your Ubuntu EXT4 partition
quit gparted
open a terminal window
type sudo fsck -f /dev/sdaX # replacing X with the number you found earlier
repeat the fsck command if there were errors
type reboot