how to increase wbc and what kind of food that help wbc increase
Depending on the reason why your white blood count is low, of course, the first thing that would help rise the white blood cell count is addressing the root cause. As far as nutrition goes, you need to include foods rich in vitamin B, especially vitamin B12 (these vitamins are naturally present only in meat, or you can take the purified supplement). You should also consider taking folic acid supplement.
Generally, you need a high protein diet mainly based on meat. But it would be best to include lean, red meat, together with folate rich foods. Raw fruit and vegetables will help boost your immune system and that will generally help to contribute to higher white blood cell count,
Wish you all the best,