When finger nail appears thin and rough, is it a sign of unhealthy which shows some problems of internal organ?

Possibly: Changes in you nails can indicate internal problems, however more likely causes include fungal infections or vitamin deficiency. Consider biotin to strengthen the nails.

Possible: Some causes of abnormal nail growth include trauma, infection, side effects of medication, and possible systemic diseases such as psoriasis. Have them inspected by a professional to determine the cause of the problem, as treatment varies depending on the diagnosis.