I have severe.vitman d defeciency (8.39 ng)30 year, male what is the quickest way to over come this defeciency?

Find cause: It's key to rule out fat malabsorption. I'm assuming your health & growth are good until now. If your physician has done this, then look at lifestyle factors. Vitamin d deficiency is extremely common and often results from misguided "healthy" lifestyles avoiding sunlight and vitamin-d enriched dairy products. A supplement may be all you need for a normal lab / to feel better.