sticks on restart
I have a 7 year old MacBookPro, running Yosemite. When I try restart, the Mac boots up about one third of the way as shown on the progress bar, then stops. It does not move any further and after about 10 minutes, it reverts back to a black screen. I have tried Command plus R so I can reload Yosemite OS, but the Mac still refuses to get past the first third of the progress bar.
I am sending this request from my daughter's Mac, so please don't assume that it is coming from my sick Mac. How can I get it to restart so I can access my Mac?
MacBook Pro, OS X Version 10.9