Could 29y old stop taking atorvastatin after 3 years treatment now good level of trig. and ldl and hdl also keeped with diet eating ?

Maybe possible: Statins do have a number of nasty adverse events on occasion, and other meds exist to lower lipids. Diet and exercise often can substitute for meds. Red yeast rice, similar to a statin might be employed, and increasing fiber intake may also be of benefit. Your doctor can help guide these changes.

Get lipids checked: Then start cutting dose to 1/2 daily for three months, ; reck!--- is there a family history of lipididemia, early heart attacks or diabetes?- a 29 year old with lipid problems usually has other problems?

No: If there is a positive family history and you have significant lipid elevations i would urge you stay on statins permanently. Their long term value is enormous and the risk are small.