Hi. A dark line appear on my right hand's index and ring finger's nails. Neither hurt nor pain in them. Suddenly before one year I saw this dark line and after one year this does not disappears. Yesterday I read a news on fb that some type of cancer is darkening of nails. After read this news I am worried about my health.

Don't worry its not like that dear.

You have fungal infection of the nail and need creams for it after showing a dermatologist .Presence of linear pigmented lines on the nails can be due to multiple causes. In white people they are considered abnormal and require thorough assessment including biopsy. In dark skinned people it is a common variant. The most common cause of these lines is racial factors. Others being drugs, trauma, lichen planus, subungual nevi and malignant melanoma. You do not have to worry too much, but do keep a watch on the pigmentation. If you notice any variation within the pigmented line or pigmentation on the adjacent nail fold or finger pulp, then consult a dermatologist in person and get yourself evaluated. Regarding moles at other sites, it is sometimes possible that they can disappear. So you do not have to worry about that.