Hello @EmbelleL ,

There is no  any solution for this . This problem is faced by multiple users and also servicenow admin has posted message regarding to this like issue is rising due to schedule maintenance . So You can jsut keep some patience and wait for while . My instance also went to offline but after some time it will get online . In rare situation it will not get back online . 

If this helps you then mark it as helpful and accept as solution .

Regards ,

Aditya