Sony Vaio laptop will not power up

Just wondered if anyone cap help. My wife has a Sony Vaio SVE 1511L1EW that we have completed a system restore and disc clean up ready for selling as she has just switched to a Mac book. After completing the system restore process we switched the laptop off. Now it will not power up, we press and hold the power on button but nothing happens, no lights illuminate, nothing. Does anyone have any suggestions as to what may have gone wrong? Have looked on Sony website but can't find any helpful guidance.

Your comments appreciated.

Ken