My Vivo activ 3 does not read my heart rate anymore.what happened? How can I reset it . I really liked the graphics where it shows how long you are in what HR zone .

There is also no distance, and no calories shown on that screenshot, hence I suspect that either the Sensor Hub firmware got corrupted during an update, or that there is a hardware malfunction.

First of all, check whether the watch itself (not the app!) really does not read any HR. If the HR is all right on the watch, and just does not appear on the app, then removing the watch from the app, and then adding it back could help (see the document Remove and Add a Device From the Garmin Connect App | Garmin Customer Support for instructions).

If there is no HR on the watch either, then first of all, try the so-called Hard Reset (as described in the article How to Reset My Garmin Outdoor Watch | Garmin Support). Then connect the watch over the USB cable to a computer with Garmin Express and check for updates. Once completed, hard-reset the watch again, and test whether it helped. If not, try the "Unprompted Reset", which will delete also some preferences. If still no go, then contact the Product Support