I am using a Macbook Air 7.2. After installing Windows 8.1 using Bootcamp, I used MiniTool-Partition-Wizard-Professional-8.1.1 and Windows Disk Management to delete a 39 GB partition. Only later did I found out that it was OS X Yosemite. Now I only have Windows 8.1 and the 39 Gb partition is used for storing data. My questions are: - Can I reinstall OS X? If yes then how? - If I don't reinstall OS X, will my warranty be void? Thank you.