Laptop shuts down suddenly after closing all the programs

Registration date
Saturday August 2, 2014
Last seen
March 3, 2017
hello every one
this last period i got a new probleme on my laptop let me tell you the spec first
CPU: intel centrino T6600 2.2ghz
GPU : nvidia gt240m 1gb vram
Ram: 4GB ddr3
the probeme is when i starup the laptop everything goes normal same when launching league of legends for exemple but when i finish playing i close The lol client
the pc shut down after few seconds and i can hear the ''clik'' sound of the HDD after 3 seconds of that the laptop relaunch automatically an shut down suddenly before windows starup 1 or 2 times then it launch normal but still shut down when closing a program however when i close LOL client and keep talking on skype the laptop work normallly but when i end the conversation it shut down
Please help as fast as you can