Opening Recently Used Files
The first place to look for the workbook you want to open is on the Recently Used file list. This is the list of the last four workbook files that you had open and edited. This list appears at the bottom of the Getting Started task pane (in the Open section), the task pane that opens automatically when you first launch Excel. You also have access to this file list on the File menu at anytime when using the program.
If you see the name of the workbook you want to open on this list, just click its filename link to open the workbook in Excel (and automatically close the Getting Started task pane).
If you routinely edit lots of workbooks in a day, you may want to increase the number of files that appear on the Recently Used list. Open the General tab of the Options dialog box (Tools → Options) and then increase the value in the Entries text box - the box to the immediate right of the Recently Used File List check box.