When installed apps are no longer available and I did not uninstall them

[AC Question]

Last night I had my Facebook, Line, Pinterest, games app.This morning they were still in the app window but the icon was blank and a SD logo on the place where the app logo was. I did not uninstall them. I had no problems before I put it on the charger and went to bed. How do I get them back online without getting rid of all my data in the process.