When I turn on my MacBook Pro, it boots up into a language screen. I pick English and it goes into a OS X Utilities screen. When I click on Disk Utility, I click on a drive in the left side called 500.11 GB Apple HDD...and I can verify but not repair

When I turn on my MacBook Pro, it boots up into a language screen. I pick English and it goes into a OS X Utilities screen. When I click on Disk Utility, I click on a drive in the left side called 500.11 GB Apple HDD...and I can verify but not repair It. When I repair the disk it comes up with the Alert: Live file system repair is not supported. How would I fix this? if I go back and click restore with time machine, I don't have any backups.

Any replies would be appriciated, thanks.