Windows boot option is missing after installing CentOS 7, how can I get it back?

I recently installed CentOS 7 on a machine that has been running Windows 7. I did a dual boot installation and installed CentOS in a partition. But when I boot up my machine, it only gives me two CentOS options. It does not give me the option to choose to boot Windows 7. How can I add windows 7 back to the boot options?