Google says to clear cache and data on Play Store and Download Manager when experiencing download problems. I can't find Download Manager on my Android device.
See if you have something like this:
System settings > Application Manager > All > Downloads
Steps to clear the cache of the Download manager app:
1.Open "Settings" - either:
a) pull down the top (right) menu and click the "cog" icon
b) click on "Application" and select "Settings".
2.Go to "Applications" then tap on "Manage Applications" (older versions)
Or "Application manager" (newer versions)
3.Select the "All" tab (to the right)
4.Now scroll down to the "Download Manager" app and tap it.
5.Tap on "Clear cache" and "Clear Data".