Hi @Naresh4, let me see if I can help out here!
Does these restarts you speak of happen often or has it just occurred once? And if they happen often, is it during a specific kind of use or does it happen randomly?
As @nolramlb mentioned, it is a good idea to test the phone in safe mode to see if the restarts is caused by a downloaded app. If the restarts happen while using a specific app, clearing data for said app might do the trick. Find and tap Settings > Apps > Tap the name of the app > Storage > Clear data > Tap "OK" > Restart the phone.
Try this and feel free to keep us posted with the results!
