After trying every possible suggested route I found in many different posts on various boards the only thing that worked for me was a complete backup to iCloud over WiFi followed by a complete Restore from iCloud via USB connection to my Win7 PC. Took about 1 1/2 hours but seems to be a perfect copy of itself prior to the hickups where I had three apps hanging after download on the installation. After backup/restore, all three apps installed fine.
Apart from the time it took (patience!) the process was pretty simple, although it required a few times of personal intervention (like entering SIM Card Lock Code etc).
Check the iTunes Store app on your phone and see if you have videos or songs queued for download. My iPhone was too full for a download to complete, so the store paused the download. What it also does is PAUSES the App Store's ability to download apps, regardless of if they're new or loading from your phone.
My Apps Store icon on my Iphone 4s showed that I had two apps that needed updating, but the apps wouldn't even show in the update screen. I had shut the phone down multiple times, then finally turned it off and left it off for a few minutes. After turning it back on it finally worked. So glad I didn't have to restore it.