You have to download Android SDK (https://developer.android.com/sdk/index.html?hl=i), uncompress files (https://mega.co.nz/#F!XJoiTBBC!m0CThUpMrQgW1LP50hzo_w) on the folder that results from uncompressing (Android SDK), specifically on the folder "UncompressedFolder"/SDK/Platform-tools. Then run CMD, type cd and drag and drop the folder Platform-tools to the window, press enter, turn on your device in Fastboot mode (power button and then, without pushing power button, press Volume Up button, Blue LED should appear), then type the following commands and finish:
fastboot flash userdata userdata.img fastboot flash boot boot.img fastboot flash system system.img fastboot flash cache cache.img fastboot reboot
Sorry for my english. You need to unlock your bootloader before do this process.