Hi all.
After the answers about "Fedora 20 Installation Problem" which I have got, I have created a Live USB using LiveUSB Creator. After that, I have started my Sony Vaio SVE1512Y1ESI notebook (which was already installed Windows 8.1 on) from my USB and I have be able to install this OS at last. At this point I have restart my PC to access Windows partition and, much to my surprise, it has appear a kernel error message on the screen. That's why I have had to restore previous situation to be able to access again that partition. What do you suggest I should do to avoid this problem befall again?
I express my early thanks to people who will know to give me an answer.