i have been through this kind of issue a while ago it happened to me when i had a update of my o.s in mac laptop . my screen was stuck at a point with apple logo . try doing few steps and lets see if this works
hold the power key and wait for like 45 sec and let the system be restart if it does not gets restart restart it manual.
try rebooting the laptop in safe mode using shift+restart
see if this will solve the problem for any other steps visit [http://fixingblog.com/mac-stuck-startup-white-screen-apple-logo/|http://fixingblog.com/mac-stuck problem] and see if you can find some useful tips . thanks a lot