If i change my diet will that cure hypertriglyceridemia?

Possibly: Modifying your diet can significantly improve your triglyceride although there is a familial triglycereidemia which is genetic based and not easily modifiable by diet. But the majority of people with hyper triglycereidemia can be helped by dietary modification. It is more important to reduce carbohydrates than fat to improve on triglyceride as it is Insulin secretion that leads to its formation.

Probably yes: Triglycerides are very responsive to weight loss, low carbs and alcohol restriction. If these don't cure it they will likely lower the levels by at least 50% if not more. Estrogen and Accutane can also increase triglycerides.