Hi there! I'm sorry to hear that you're having trouble with your line chart in Excel. Here are some steps that might help you display the lines:

1. Select the data range that you want to use for your chart.
2. Click on the "Insert" tab in the Excel ribbon.
3. Click on the "Line" chart type in the "Charts" section.
4. Excel will automatically create a chart with your data points, but without lines connecting them.
5. Click on the chart to select it.
6. Click on the "Design" tab in the Excel ribbon.
7. Click on the "Select Data" button in the "Data" section.
8. In the "Select Data Source" dialog box, click on the "Add" button under "Legend Entries (Series)".
9. In the "Edit Series" dialog box, enter a name for your series in the "Series Name" field.
10. In the "Series Values" field, select the range of cells that contains the data points for your series.
11. Click "OK" to close the "Edit Series" dialog box.
12. Repeat steps 8-11 for each of your four time series sets of data points.
13. Click "OK" to close the "Select Data Source" dialog box.
14. Your chart should now display lines connecting the data points for each of your four time series sets.

If this doesn't work, you may want to check that your data is formatted correctly. Make sure that your data is in columns or rows, with each series in a separate column or row. Also, make sure that your data is sorted correctly, with the x-axis values in ascending or descending order.