The black horizontal lines can be something benign or in rare cases can also be a sign of melanoma (a form of skin cancer) . The ridges, indents can be due to nail lichen planus or nail psoriasis. I don't mean to scare you but i wish to emphasize the need for a proper evaluation .Kindly get it examined and assessed by a qualified dermatologist in person for a proper and thorough evaluation. As you are located in Istanbul i don't know any dermatologist there but you can ask your primary care physician for a reference. Hope this was helpful.