keyboard shortcut to select file in windows explorer

Try shift+tab that will tab in the reverse order

After launching Explorer, press F6. This toggles between the file list, the address bar, and (annoyingly) the close button for the "folder tree" pane. While on the folder view's close button, you can press tab to move into the actual folder tree.

Alt-Enter sometimes works from the address bar. It seems a bit temperamental though, not properly figured it out. Using Windows 10

A bit long-winded but might be preferred to multiple tabbing.

On Windows 10 try: Alt-H S A Down

Alt-H opens the 'Home' ribbon menu, S A selects all. Then using the up/down arrow keys to cancel the selection. Note Alt-H are pressed simultaneously then released, S A Down are pressed one at a time.