Back-Up, Replace, or Recover
Generally, if this problem cannot be fixed with a CMOS reset, then you're pretty much stuck. The only other option you have is to recover or back-up as many files as you can and replace the hard drive entirely. One option would be to send it into Sony (they have pretty good customer service), but to do this yourself you'll first need to either boot from a disk as opposed to the hard drive itself, or boot from another hard drive and use your main drive as a slave drive.
To do this, you'll need a second PC (preferably a tower for optimum flexibility) and an adapter to connect your laptop to it. This should let you route the laptop's drive onto your computer as if it were an external hard drive, and once you do that, attempt to copy as many files as you want to keep onto another drive. If you still can't access the files (you click the hard drive, but the files don't appear) despite it being attached to another computer, you'll need to try some drive recovery techniques. These are relatively easy and often don't cost anything, but it is something you'll need to know how to do before continuing on with the procedure.
Anyhow, once you've either backed up all of your needed data, or you've recovered the drive enough to either use it or back it up and save it, you'll need to go out and get a new hard drive for your Vaio, and then install it in place of your old one. After you've done this, start up your PC, install Windows if needed, and you're set to go.