
The last time I closed it with the Task Manager. How could I make it work again?

Yes, may be there was not a defect but it just lasted extremely long, much longer it normally lasts, an hour or much longer than an hour, do not remember anymore. At the moment Everything seems to work like usual.Everything should eventually finish updating, depending on the number of changes it might be faster to completely rebuild in the Everything index.
I hadn't initiallized that by intention.Modifying attributes, such as removing the Indexing attribute from all files on a volume.