mini2440 Tft issue

i have one board which is using mini2440 & 3.5 inch Tft along with it.

I have discovered some problem in TFT in other rejections from customer (5
rejected UFF??). I haven't updated any code or tweaked any thing in
hardware. But now TFT does not respond to touch. Machine can also be
operated by mouse or keyboard. When I connect keyboard or mouse, TFT
operations works fine. Like if press 'A' on keyboard, TFT do operation for
it fine.
Now touch is not working at all.
Only place touch is working when I open a menu on TFT with help of
keyboard. If then I touch on one of menu item, TFT detects the touch in
menu item right below it.