Half install and turn off when reboot keep saying it was turn off and reboot again and again

my MacBook Pro 2012 instilling 25% and turnoff. When I turn on it's take my password, and almost half of filling status bar and black screen showing kernel something, and say press any button, and reboot again and again! I try to command R to install showing HD and image both are look and i cannot select anyone for installing. What I suppose to do, I am helpless, I need my system either old OS OR new capitan. i dont have any time machine, if some one help I would highly appreciate. Kadir.