It sometimes happens when you minimize your application to switch to another tab and you mistakely press the tab cleaner,  whoops your recent application are gone,  but the good news is;
Some devices has a good feature of locking tabs to avoid accidentally closing important tabs on your mobile...(you can check your phone brand)
Here is the guide:
Minimize your application and lock the important application to avoid accidentally closed and clear the memory. 
Locked application remains.
Unlock application to clear all tabs. 
Nothing remains.