Awww...I'm sorry he forgot!! My husband forgot one year too...and let me tell you...he has never "forgotten" again
....22 years later!! You really won't have to do too much to him....he is going to feel really bad when he remembers! You should go ahead with whatever plans you had, going out or whatever and then at the end of it, give him his gift (if you were giving him one) and just say "Happy Anniversary!" He'll be making this up to you for a week, I bet!
Happy 5th Anniversary!!!!