If it was me I would do a reset of the tv, the pin should be 0000 unless you changed it in your original set up. This will give you another opportunity to scan for channels. You can always power cycle the tv first, unplug for five minutes and plug back in again, go to settings and see if it sees your aerial. If not then reset and go through the set up process again. Make a note of your picture settings before you reset as they will clear when you do this.
