If you have a live or recovery cd/dvd/usb drive, you can boot into that and fix the file systems with fsck. However, as AHarrisGsy mentioned, it would be good for you to provide a bit more information.
Thank you. The major problem is that my openoffice suit can open. The Ubuntu software center can not also display when I click on it to open. Lastly the destop screen can not display.
Please advise. I do not have the recovery cd or dvd you are talking about. How can I download one?