You were downloading iTunes apps and iTunes quit how do you get the app again?

As long as you were signed into your apple ID when downloading the app, it should be saved within that ID. So go back to the app store, make sure your signed in, then check your account for already purchased apps. It may start downloading automatically also.

If you are using Vista or Windows 7 OS, to get the app back go to;

1. Start button
2. Type into the search bar - .ipa
3. Double click on the app that was paid for and downloaded but isn't in your iTunes library.
4. It should be there now.

Hope I helped.