I am a 42 years old male , have occasional unpredictable chest pain (pressure type) since 1 month ago. no htn , no hyperlipidemy , no other dis. why?

Myriad of reasons: There are many reasons for this other than cardiac. BUT, if you have not had any cardiac workup I would still recommend starting with this and getting a stress test. If that is negative then the possibilities include lung disease (asthma, COPD, interstitial disease), stress / anxiety, sleep apnea. Start with the heart and go from there!