LCD not showing anything...... after working normally for three or four times

I was using a 16X2 LCD for my project. It worked just fine at least thrice and then it just wouldn't show anything. I tried running the basic examples of the LCD library and also changed the default pins of the library too but the problem persists. It does not show even the black boxes. I have even replaced the LCD. Can there be any problem with my arduino????

Sure.

It does not show even the black boxes.

This would tend to rule out a problem with the program on the Arduino or the choice of pins to use since all it requires is power (LCD pins 1, 2, and 3) to produce a line of black boxes.

Are you sure you didn't change the contrast setting somewhere along the line?

Don