suddenly stop all working and stop mouse,keyboard that means freeze.

Dear IT expert,

plz help me that , Laptop : (Acer Aspire E 15)

when i am doing work on my Laptop. suddenly it stop all working.just freeze . don't work mouse,keyboard or any thing.. just work power button. not show black or blank page .

PC configuration is : core i 5 5th generation , ram-12 GB, HDD - 1 TB , Graphic -NVIDIA + 2 GB dedicated VRAM.

plz help Expert.. how can i do right now.