A workbook is a pretty big place. No matter how large your computer monitor, you will never be able to see all the rows and columns of all the individual worksheets at the same time. Sometimes it helps to remind yourself that even though you might not be able to see all of the data, it's still there.
The vertical and horizontal scrollbars on each worksheet provide some navigational aids. Each scrollbar has directional arrows on either side of the bar. Click the directional arrow that points in the direction you want to go.
Another way to jump from cell to cell in a worksheet is by typing the address of the cell you want to move to in the Name box. (The Name box is located above the column labels at the left side of the screen.)
To move from worksheet to worksheet, click the tab of the worksheet you want to bring to the front.