Summary of the comments as solution
You have a WUBI installation that was initially 12.04. It was upgraded from within WUBI to 12.10. However, while upgrade to 13.04 the upgrade failed. Now Ubuntu is unbootable. Windows is bootable. There is no valuable data in the Ubuntu.
Note: The way WUBI works is cumbersome and prone to breakage. It was meant for short term use to try out Ubuntu. It does not work with newer computers. So it was taken out of 13.04. That is, one cannot do a fresh WUBI install with 13.04. I am not sure if that is the reason your upgrade failed or not. In any case, upgrading WUBI install fails sometimes.
First, backup all the important (and not so important) files in Windows. To be safe, make a recovery disk for Windows as well. Even though, nothing should happen, mistakes do happen, power goes off, a cat walks over the keyboard...
Second, Uninstall the WUBI version of Ubuntu. Boot Windows and delete the WUBI installation using Add-Remove in the Control Panel. This will remove almost all of Ubuntu except the boot menu choices. The space that you allocated to Ubuntu during WUBI install should be returned to Windows. If after the uninstall disk space is not freed, remove the contents of C:\Ubuntu. See How do I uninstall Ubuntu Wubi? for full description.
Third, Install Ubuntu in its own partition as dual-boot with Windows. See the official documentation on how to install. Make sure in Step 4, you choose "Install Ubuntu alongside Windows." This will keep your Windows installation and all the data in it. This will also make next step (partitioning the hard disk) easy. Also see How do I install Ubuntu?
Finally, Some of the things may not work in a new install of 13.04 (chrome, Skype). See 7 things to do after installing Ubuntu 13.4. for some help with those.
Best of luck.