What do I have many vertical colored stripes on my screen

Hi,

Try taking a picture, (I realize that you cannot "see" what you are taking) and then download it onto a PC to see if it is alright?

If the picture is OK then you have a problem with the LCD screen in the camera.

Here is a link to the Ifixit guide on how to replace the LCD screen in your camera.

Samsung NX300 and NX300M Back Panel Assembly Replacement

Here is a link to suppliers of the part. It is not a recommendation to use any of them it is just shown to give to an idea of the price and what it looks like. Just search online for Samsung NX300 LCD screen for more suppliers which may suit you better.

http://www.ebay.com/sch/i.html?_from=R40....

If the picture is not OK, does the menu screen work OK?

If it does then you most probably have a problem with the CMOS sensor in the camera.

Here is a link to the Ifixit guide on how to replace the CMOS sensor in your camera.

Samsung NX300 CMOS Sensor Assembly Replacement.

Unfortunately I have been unable to find a replacement part, perhaps you may have better luck

If it doesn't then you most probably have a motherboard problem. Here is a link to the Ifixit guide on how to replace the motherboard.

Samsung NX300 Motherboard Replacement

Again I cannot find a replacement motherboard either.

hopefully this is of some help.