Fingernail ridges are usually a sign of bad health. Horizontal ridges in your nails are caused by trauma to the cuticle as well as by medications or sickness. Meanwhile, verticle ridges are hereditary but can be caused by trauma.
If you have either type of ridge, you can take steps to cover them up. Things you can do include applying nail polish and using an emery board. Nothing can cure these ridges completely, but these methods will help you deal.