I used to puss Back button present in left corner of window with arrow sign
Click the green arrow on the toolbar
Ctrl + F11 = Toolbar
If it is on Microsoft Word you just press undo up in the toolbar a little curved arrow pointing left
Customize Quick Access Toolbar
at the top left corner, the left arrow button
Right click on your toolbar and click on the email option
On the drawing toolbar, go to autoshape->connectors, and the double arrow is in there.
on the google toolbar click the down arrow or click the down arrow on the very right close to the top
In help window you have a toolbar there. Search for an blue arrow pointing towards left.
Maybe your navigation toolbar is off try it. Go to View. Then toolbar then find the Navigation tools bar button
Try turning the toolbar off, then back on again. If that doesn't work. Reinstall it.