Touch pad is not working on DELL latitude 7490

The touch pad is not working .the cursor moves but it does not click or open any file it doesn't zoom or scroll either . I have checked the settings the touch pad is enabled and drivers in mouse are also working properly and installed but still it is not working .left key is working but not the right one only cursor moves can you tell what's the issue and how to resolve it ? I only like doing work by fingers it's uncomfortable to use the buttons every time.someone please help me it stops working randomly when i use laptop constantly please