Inspiron 1545 screen not working

I have an Inspiron 1545 and the screen is damamged, it's bleeding in one corner, the whole screen is grey when it starts up and then turns blue when it gets to the login screen. I can't  see any details on screen just one colour, when I plug it into an external monitor it receives a signal from the laptop but the monitor stays blank. Is this just a problem with the screen and can I just replace that or are there other problems here?