My screen has just gone

This is either your lcd or the flex cable,either way you would need to take the casing off around the lcd,you will see a flex cable connected to the lcd if you have a camera phone there will be another one comming from that,you will want to using tweezers disconnect the one to the lcd ignore the one to the camera.plug it back in and see if it works this is just to test the connection,if this does not work inspect the cable for any tears or cracks if it looks completly fine it is probably your lcd there is no way to tell for sure though unless you see damage to your cable as there is no way for you to test your lcd unless you have another phone to try it in.But those are the only two possibilities.