In order to unhide necessary files or folders you may do one of the following steps:
Change their status without removing them from Hide List
Simply right-click necessary file/folder and select "Change status" option

Remove them from Hide List
Right-click necessary file/folder and select "Delete" option
Remove all items from Hide List
Either of the next steps will clear Hide List
Select "Files"->"Clear List" from the Main menu
Click "Clear List" toolbar button
Right-click anywhere within Hide List and select "Clear List"
Turn off hiding globally
Select "Files"->"Stop Hide" from the Main menu
Click "Stop Hide" toolbar button