When a file is used (either created new or opened) it is added to a list called Recent Files: this list maintains the unique list of files used, in order of date of use (from most recent) with the purpose of being able to quickly reopen them in the workspace.
Select the submenu File/Recents then the desired file in the list: as soon as it is selected, that file will immediately be loaded into memory and opened with the appropriate editor (for more details, see Open an existing file of generic type).
NOTE: The recent file list is unique for each workspace; it is not available if there is no workspace open.
File History.
The recent files menu can display up to a maximum of 10 files: in the event that the recent files list contains more than this, the submenu itself activates the File/Recents/File History... command, which provides access to a window containing then complete file history.
In the window, select the desired file, then press Open (or hotkey Enter) to open the file, or press Cancel (or hotkey Esc) to cancel the current operation.