Open Worksheet...

Description: The File | Open Worksheet... menu option opens a worksheet for the currently opened project. A dialog box will appear (shown below) listing the worksheets associated with the project.

Choose a worksheet and click Open or just double click on a worksheet file to open the specified worksheet.
Please note that the worksheet you are opening needs to belong to the currently opened project. Choosing a worksheet from another project will not work. A worksheet will appear, but it will be empty. If you accidentally open a worksheet not belonging to the current project, make sure you do not save it, because you will destroy its contents.