Laptop not restart it get stuck

Hello,

My name is Imroz.
I have lenovo G510 , it was working good but from few days when I restart my laptop it doesn't restart, it get stuck i wat for 10 to 20 minutes but nothing happens. Lastly I press the power button to completely shut down the PC and ON it normally...
the main problem is when I restart it...
Otherwise every thing works properly when I normally starts it by using power button...
Please help I am very worried about it..