Problem in Accessing API

Earlier i was accessing API through Ajax and it was working properly. Dont know suddenly what changes have been made to the API my Ajax call for API are not working.
$.ajax({
type: ‘GET’,
url: ‘https://kc.kobotoolbox.org/api/v1/data/511840?format=jsonp’,
headers: {
‘Authorization’: 'Basic ’ + btoa(userName + “:” + password)
},
dataType: ‘jsonp’,
})
It is giving me Failed to load resource 404. Infact accessing the API directly is giving me the json data. Also i tried to load the data in Excel as per the documentation shown for Pulling Data Into Excel Power Query. It is also giving me the same error - Web.Contents failed to get contents from ‘https://kc.kobotoolbox.org/api/v1/data/511840.xls’ (404): NOT FOUND"
Is there some changes done in the API because my same program was working fine earlier.
It would be a great help if you could solved this soon.