How can I get my FULL tv screen back?

My Samsung TXS2782H 27" Slim Fit HDTV! I purchased this tv about 3 years ago from the pawn shop! After about a year, i've noticed the picture was cut short at the bottom of the screen. So I did everything tryin to get the picture back to normal. It's pissing me off! I watch a movie I put subtittles on The only visual picture i can paint for you is..........imagine your screen is on zoom 2x and it can't get off!!!!!!!