It grows back in usually two weeks but sometimes may take 4-6 weeks.
Apply olive oil and take some vitamin supplements
for some days. Also eat a healthy, nutritious diet and drink plenty of fluids. The most important nutrients are biotin, silica, magnesium, sulfur, zinc, and vitamin B6. There are many eyelash growth products in the market, but their efficacy has not been scientifically proven. So consult a dermatologist before using any of them.
I sincerely hope it helps.