When you first create a chart in Excel, the X-Axis by default appears at the bottom of the chart. In case the X-Axis disappears, you can always bring it back with the steps below:
Step 1: If you work with Excel 2016 or after, you can use the element handle. Click on the chart and you will see 3 icons appear on the right of the chart;
Step 2: Click on the plus sign, you will see the list of the "Chart Elements" such as Axis, Axis Titles, Chart Title, etc;
Step 3: If the Axis disappears, the box in front of the "Axes" should leave unchecked. Check the box and the Axis will appear in the chart;
Step 4: To have only the X-Axis or Y-Axis, click the triangle after the "Axes", and select "Primary Horizontal" for X-Axis or "Primary Vertical" for Y-Axis.
If you work with an earlier version (or any version), you can get the chart title back with the steps below:
Step 1: Click on the chart and you will see the "Design" tab from the ribbon;
Step 2. In the "Design" Tab, click "Add Chart Element";
Step 3. Click "Axes" and select "Primary Horizontal" for X-Axis, or select "Primary Vertical" for Y-Axis;
Step 4. You will see the Axes now appear in the chart.