Can't download any app for iphone 4?

I'm trying to download a free app from the app store and it gives me "unable to download application" error. I've tried deleting it then trying to download it again but it gives me the same error message. I've also reset my network settings! Any help with this would be greatly appreciated! I'm really getting frustrated at this point!

Maybe is not compatible with your firmware or you can try hard reset Good Luck!

You must have started downloading it and it stopped for whatever reason, delete the app then go to the app store and re download it. It happens when you interrupt a download.