I just tested Google Directions API and it works well on my side.

There are usually two problems with the Directions API:
1. Problems with the key.
2. Problems with start or end location. For example, incorrect coordinates or place names, or Directions API cannot find a route between them.

Both problems can be easily identified by looking at the response from the service.
What response from the service do you have?

But yesterday we just use this system normally .

1.our package version is 3.7.01.
2.We use google map to be our provider.(But we tried others provider is also request null)
3.We can't get map's  image Imformaiton normally , just can't get navigation text imformation(like "go north",Distance).

Plz help us! I will really appreciat for it.

  private void OnGoogleDirectionsComplete(string response)
        {
            //Debug.Log(response);

            // Try load result
            OnlineMapsGoogleDirectionsResult result = OnlineMapsGoogleDirections.GetResult(response);
            if (gameObject == null) return;
            if (gameObject.activeSelf == false) return;

            if (result == null || result.routes.Length == 0 || gameObject.activeSelf == false)
            {
                print("result is null");
                print("result Length: "+result.routes.Length);
                return;
            }
         }