@Rakesh-Natarajan said:
How to Solve this
{ "status_code": 7, "status_message": "Invalid API key: You must be granted a valid key.", "success": false }

Only the Travis Bell admin and you can access your API Key.
So I suggest you

Take a Test
Using a computer, desktop or notebook.
On some mobile devices this test may not work correctly.
In the URL below, change THE_KEY to your API Key.
https://api.themoviedb.org/3/movie/550?api_key=THE_KEY
Use this example to do a search using a new tab or window in your browser.
You will receive the basic data of the Movie Fight Club (1999)
https://www.themoviedb.org/movie/550-fight-club
If it works, your Key is OK.

When there is a problem, the TMDb Server sends a message.
Can you tell which message the server sent?
Here is a list of possible messages:
https://developer.themoviedb.org/docs/errors

If it does not work, let us know right here.