You have to repair not only the booting using "StartUp Repair" from Windows Recovory CD/USB but also should run from recovery prompt:
sfc /scannow - which scans system files and repairs them. If errors are found you can run the sfc /scannow command two-three times but you have to reboot before every run for best results.
After you have Windows up and running you can add a boot menu entry to Windows 7 BCD (boot configuration) using a so called "boot sector loader" (the file needed as boot sector file is either stage1 (GRUB) or boot.img (GRUB2) found in Linux /boot/grub directory).
See here how to create boot sector loader for booting Linux based OS.
To get to the boot menu in Windows you need this files and directories:
Windows PBR (partition boot record)
bootmgr in \
\boot folder with BCD (boot config data) inside.