Can't boot into Windows 10 after making new partition

Hi. I recently added a new 10gb partition to my Mac after have both Windows 10 and Yosemite installed. I wanted to run windows software but my windows 10 installation had a few little bugs with my software so I installed windows xp on a the new 10gb partition. However, it turns out the software ran much better in the Windows 10 than Windows XP. However, now I can't boot into windows 10. PLEASE can someone help, I'm desperate!!!