BusyBox on boot after update

[jrasmussen]

I just installed a few updates that popped up in Plasma-Discover. On reboot I am at a black screen with this info:
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'm afraid I do not know what happened, or what to do from here. Could someone please offer some assistance? I'm fairly new (if that wasn't obvious!), so will need detailed instructions.

Thanks.

[leszek]

Seems like the initrd broke on your system. Or a newer kernel has problems finding your root partition.
Try booting one of the older kernels.

[jrasmussen]

Seems like the initrd broke on your system. Or a newer kernel has problems finding your root partition.
Try booting one of the older kernels.

Thanks for your response.  Could you instruct me as to how I would boot an older kernel from this (initramfs) screen, or what I need to do?  I really appreciate any advice you can give.
John

[leszek]

In the boot menu you should have the option to to go to advanced where the older kernels should be listed.
If Maui is the only system installed press shift key or esc after bios/efi screen to see the boot menu.

[jrasmussen]

In the boot menu you should have the option to to go to advanced where the older kernels should be listed.
If Maui is the only system installed press shift key or esc after bios/efi screen to see the boot menu.

Thank you so much--that worked!! 
The offending kernel seems to be 4.4.0-45, while 4.4.0-42 is working fine.  A couple more quick questions.
-Should I remove the 4.4.0-45 kernel (and if so, how do I do that?)?
-Are the Plasma-Discover updates not to be trusted then?

[leszek]

You can remove the non working kernel in synaptic by searching for it there.
We provide mintupdate as default which will by default not update system components that might break the system.

[jrasmussen]

You can remove the non working kernel in synaptic by searching for it there.
We provide mintupdate as default which will by default not update system components that might break the system.

Perfect--back to normal and very grateful for your help!