Annoying white lines on top of tv

Latley everytime i turn the tv lines i get these white lines on the top of the tv sometimes a few sometime a lot not sure why is doing it before it never did it.  and its only in the bedroom all other tv are fine.  i'm thinking it might be the tv itself cause evrytime i play a tape tht was recorded on another tv i still get the lines and whn i played my dvd player i also have gotten  the lines.  does tht mean my tv is getting old and thts why its doing all those top lines i'm not ready too buy a new tv yet.  the only good thing the lines doesnt show up on letterbox format movies and tv shows so thy dont annoyed me as much.  and all wires r connect correct.  should i try too reset the tv???