If clearing the cache and data in your Google Play Store didn’t work then you may need to go into your Google Play Services and clear the data and cache there. Doing this is easy. You need to go into your Settings and hit Application manager or Apps. From there, find the Google Play Services app (the puzzle piece).
Besides, why does Google Play Say download pending?
Try going to Settings>Apps>All, select Google Play Store, and Clear Cache/Clear Data, then Force Stop. Do the same for Download Manager. Now try again. If that doesn’t work, try going to Settings>Accounts-Google, select your Google account, and remove it completely from the phone.