I've observed that running a filesystem check (fsck) on the disk doesn't permanently resolve issues, as they tend to recur within a few days. Interestingly,...
The instructions @ericklan posted are on the right track, though they aren't quite clear to me and seem to recommend more than is necessary....
Grub Customizer is a great application, it allows you to add or edit menu entry and change the default OS boot with GUI....
How to install Xfce on Ubuntu
How to access Ubuntu from Windows remotely