Q: I can't download the application because a purchase problems

What is the  'purchase problem' ?

neither can i. its just saying problem with last purchase or billing something like that. but iadw im game purchases and it works fine

What does 'iadw' mean ? Are you aware of any problem with a previous purchase ? If you log into your account and view your payment details are there any error messages on the screen ? If not then have you tried contacting iTunes Support and asked them if they know what the problem is ?