How can i make a keypress action to this code?

To detect key press using JQuery, you can bind a function to the keydownevent :

$(document).keydown(function(e) {
    switch(e.which) {
        case 37: // left
        break;

        case 38: // up
        break;

        case 39: // right
        break;

        case 40: // down
        break;

        default: return; // exit this handler for other keys
    }
    e.preventDefault(); // prevent the default action (scroll / move caret)
});

(taken from there)

To change the displayed img, what you could do is something along the lines of this :

$("#largeImgPanel").html('<img src="./images/t_p0001.jpg"  style="cursor:pointer"');

Then you'd have to implement a system to know which image is being displayed, and use this information to determine the next image to show.

EDIT : as requested, to make it go through the images :

var imgs = ["./images/t_p0001.jpg", "./images/...", etc];

var currentImg = 0;

Then in the keydown event handler, you'd have :

case 37: // left
if (currentImg === 0) {
    currentImg = imgs.length - 1;
}
else {
    currentImg--;
}
break;
case 39: // right
if (currentImg === imgs.length - 1) {
    currentImg = 0;
}
else {
    currentImg++;
}
break;

Then you just have to update the src property of your img tag (after the switch) :

if (e.which === 37 || e.which === 39) {
    $("#largeImgPanel>img").attr("src", imgs[currentImg]);
}