I had purchased an in-app items,
It said "you've already purchased this but it hasn't been downloaded. press ok to download it now"
what should i do?
It aint downloading...
I believe you should get the in-app again from the app but it depends on the kind of in-app that you are downloading. Here is an article that you can review about in-apps:
You can also contact support if you'll need more assistance with this:
Retrieving data ...