Ana positive c3&c4 low triglycerides now high and dr said I had fatty liver due to weight gain no symptoms of lupus could it be causing fatty liver?

Whoa. Plenty of perfectly healthy, not just lupus-free, people have positive ANA especially at low titer, and lowish c3 and c4 (which are poor lupus screens anyway). Nothing says "lupus" to me, but I am very concerned about your fatty liver and weight gain. By far the best treatment for "nonalcoholic steatohepatitis" is to find some fitness activity you like and do a lot of it. Good luck.
More than one issue. In play: non-alcoholic steatohepatitis is a growing problem along with increasing weight of people. It is important to keep the weight under check for both lowering your triglycerides and addressing the fatty liver. Other issues with your health affecting your immune system are likely not helping your cause.