engine not working

This is my first time here,happy new year to one and all.could some one tell me what is wrong with this engine.This a 80cc 2 stroke bicycle gas engine I buy and it did work at first but I had to leave the island for business for four months after trying to restart it again the engine would not start,what could be the problem and do I need to chance any parts after having it down for so long.

Thank you
longtime