Hi,
Worth checking all the config paramenters - but probably the commonest error is that if you are using Ports RA0 -RA4 for your lcd, your must select them for Digital I/O by means of ADCON1 as the chip defaults those ports to analogue at power on.
Does your lcd show a row of black blocks across the top row - that usually means the lcd is ok, but your progam is not running.
You could also try using the 4meg internal oscillator incase you have damaged or have a faulty xtal.