OS X installer has deleted windows

Hello,

im sorry if I have put this ini the wrong place. recently i decided I wanted to have a taste of OS X Yosemite beta and I found a YouTube video that gave me a link to download it. I downloaded it and it looked as though it would install perfectly since it was set to install to the macintosh HD partition. I also had a windows partition since I like playing games. I then started the update, and it installed. I used it for a while, but then I wanted to switch back to windows. I held in the option key and booted up to get in to the OS selector, and to my horror, windows wasn't there. I did some research, and found out that if you previously made OS X smaller from disk utility, then made windows use the free space (which I had), doing a major os x upgrade would mess up your bootcamp partitions. Is there any way of me recovering my windows?

Mac specifications:

IMac 21.5" Late 2012

2.7 ghz Intel core I5 3335S

16gb of 1600mhz DDR3 (2x8gb)

nVidia GeForce Gt 640m 512mb VRAM