Welcome to the forum! Do a search on the internet. Should get you plenty of useful links. You won't something like this here on this site.
Welcome to the forums. Do you know whether that function has been encrypted using SQL Server encryption or any third party method? As suggested by Frank if you know the encryption source it is easy to decrypt, if not refer to http://cvakumar.com/msdynamics/2008...ored-procedures-functions-views-and-triggers/ and test the method.