You could try and leave it switched ON (UNDISTURBED) for a couple of hours as suggested here: http://www.davidsonelectronics.co.uk/code_entry.htm or try the LOCK 10 suggestion here
http://tinyurl.com/4ydhop
If neither work, then it looks as though you have used all your "chances" by entering too many wrong codes and the solution is to take it into the Ford Dealer or Radio Decode Specialist.....or might be cheaper to buy a replacement off Ebay etc
RegWorts
June 2008