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
- open a
terminal
window
- type
sudo fdisk -l
- identify the /dev/XXXX device name for your "Linux Filesystem"
- type
sudo fsck -f /dev/XXXX
# replacing XXXX with the number you found earlier
- repeat the fsck command if there were errors
- type
reboot
Update #1:
To retrieve any data you'll need:
- Ubuntu Live DVD/USB
- some external destination to store your data
Then...
- boot to the Ubuntu Live DVD/USB
- open a
Files
window
- open a second new
Files
window showing your external storage
- single-click on your hard disk in the left window pane to mount it
- find your
Home
folder in the right window pane
- drag any important files from your
Home
folder to the second Files
window