After you boot into Ubuntu 14.04, make sure you perform a complete system upgrade (sudo apt-get upgrade followed eventually by sudo apt-get dist-upgrade just in case you have heldback packages).

You can run previously mentioned commands and the next one in a terminal window (press Ctrl+Alt+T for the terminal window to pop-up). If there is no terminal emulator present on your system, you can install one using the Software Center and typing in as keyword terminal.

After you finish updating the system and reboot, you can run this command in the same terminal window:

  sudo update-grub

See whether grub recognizes your Windows OS, and if it does you're good to go, I mean you done half the job for Windows to finally boot-up. Next you should repair your windows installation with your Windows DVD, using the Repair your computer option, and after you finish with this one, you can download Boot Repair CD iso image and burn it on a regular CD or put it on USB key via Unetbootin. I assume you're using Windows 7 ?

Next you should restart your computer with Boot Repair CD in tray and after it finishes loading you can choose the 'Recommended Repair' option to finally fix your dual-boot configuration and be able to boot into both Windows and Ubuntu.

If grub does not see your Windows OS after running sudo update-grub, it could be because you installed grub on the Ubuntu partition, and you should do the same steps, namely repair Windows mbr with your bootable Windows DVD, and then use Boot Repair CD to fix your boot problems.

Almost forgot to mention that you should download the 64bit iso image for Boot Repair CD if you're using a 64bit system, and the 32bit iso image if you're using a 32bit OS.