My dvd player has option of letterbox or native? My little cousin was messing around with it and now i dont know which is the default. Which is the better option to use to watch movies?

What kind of TV do you have?

i have a sony 40v2500

It should be set to wide if that is an option on your DVD player setup since you have a 16x9 monitor.

Well it has 3 options. Native, letterbox, or Stretch. I compared Native and letterbox and don't see a difference. I want to know the difference in both?

What DVD player do you have?

Probably native. It will only matter for non-anamorphic discs, if at all. So test it with such a disc if you have one. If not, flip a coin.