Why is my screen blue

Hi,

Do you mean there is a blue letter "T" on the screen or is the entire screen blue ?

If the entire screen is blue have you checked that the cable from the signal source (whatever it is, antenna, a "box" of some description etc) is securely connected to the TV and that you have selected the correct input on the TV e.g. co-ax, HDMI etc.

Post an image of the screen, so we can see what you mean.

Here's how to do this Adding images to an existing question