I installed Ubuntu yesterday alongside Windows 7 and whenever I start my computer I don't have the option to boot Windows. When the computer starts it goes straight to Ubuntu without giving me an OS selection menu. When it goes to Ubuntu it gives me Ubuntu repair options and Ubuntu normal start option. I still have all of the Windows 7 files on my hard drive, but Windows 7 has no way to boot.
First thing first, you need to repair your WIn7 bootloader, and you can visit this page to learn how to do this. Write down on a piece of paper the required commands for fixing both boot and mbr. You'll be using those codes after getting to the Command Prompt screen.
Next you can download Boot Repair iso image as suggested in the previous answer by 'user3005324'. Choose 64 bit iso image if you have installed Ubuntu 64 bit or choose 32 bit iso image if you have Ubuntu 32 bit. I hope Win7 is the same architecture with Ubuntu, I mean you have either Win7 32 bit and Ubuntu 32 bit, or you have Win7 64 bit and Ubuntu 64 bit.
Burn the iso image, and restart your computer with the new Boot Repair CD in tray. You can write Boot Repair iso image on a USB pendrive with Unetbootin tool if you don't have a regular CD to use. Read instructions on how to use Unetbootin in Linux/Ubuntu, they are located at the middle of this page: http://unetbootin.sourceforge.net/ .
After Boot Repair cd or usb pendrive finish loading, you can press the 'Recommended Repair' option, wait to finish and after you get the message 'success' you can reboot and use Win7 and Ubuntu which will be present both in your start-up boot menu.
1> boot into ubuntu live cd and do a simple os-prober in terminal
2> does it show win7?
If yes, you are safe.
Just follow this link https://help.ubuntu.com/community/Boot-Repair
if not, you are probably screwed.Probable reason to that is windows was installed in LEGACY BIOS and u installed ubuntu in UEFI BIOS (provided your computer supports this new bios version) which means u have to reinstall everything.
But if your computer doesn't support UEFI bios, and both operatng systems are installed in legacy bios, then the above link should work.