I just got rid of the stomach virus how long till i.Fully regain my appetite again?

Gastroenteritis. A stomach virus will usually last about 2-3 days but can last about 5-7 days. Give yourself a week to feel completely back to normal.
A 'few days' The 'stomach-flu' or viral gastroenteritis is usually self-limiting and appetite should return soon (in next 1-2 days). If it lasts longer, your doctor may consider further work-up.