The shortcut Alt+PageUp is to move one screen to the left in a worksheet. In some keyboards, PageUp is also PgUp.
Step 1: Click a cell in the worksheet that is not on the first screen (move cursor to the right till you cannot see the first several columns);
Step 2: Press and hold the "Alt" key, and press the "PageUp" key. You will see the cursor now moves to the previous screen.