Unable to now open downloaded apps

[AC Question]

I think, in trying to free up space on my samsung galaxy tablet, i deleted an app that had previously opened downloads, including downloads sent to me with a video in them.
How can I get this back so I can open the download up. The download says it is complete, but the message I get tells me it cannot open the file.

Thanks

 

[B. Diddy]

Welcome to Android Central! Which tablet? What kind of downloads are you talking about? Files attached to emails or text messages? Apps that you're trying to install from Google Play Store or the Galaxy Apps Store?