El Capitan Cannot start after upgrade
Dear all,
After my mac downloaded El Capitan and restarted itself, the loading page appeared and the loading line below the apple sign started to install, BUT stopped at about 90%, for hours! I left it go to bed. I woke and found same page still loading at 90%! So I force restarted the computer, a log in page appeared, once I type my log in details the loading line started load but stops at half way Now! Anyone knows what to do Please? I need at least to go back to previous OS X system so I won't lose my files.
look foward to hearing from your suggestions! many thanks!
MacBook Pro (Retina, 15-inch, Late 2013), OS X Yosemite (10.10.5)