Web service is not available (it doesn't exist or might be disabled)

I am using Moodle 3.3.3. 

I am not using any web service for my moodle. And it's showing me "Web service is not available (it doesn't exist or might be disabled)"  

1. Login with admin user

2. Clicking some links and work on some pages...

3. By mistake my chrome Browser close by clicking X .

4. I restart chrome browser and restore my all tabs.

5. Moodle showing me : Web service is not available (it doesn't exist or might be disabled)

Please help me out.