A notification that never arrives has four places it could have been stopped, and they fail in ways that look identical from outside. Checking them in order tells you which one it was, and three of the four are a single switch.
First: whether anything is getting through
Before changing settings, work out whether it is one app or all of them. If nothing has made a sound all morning, the problem is a mode. If one chat app is silent while everything else works, the problem belongs to that app.
That distinction decides which of the sections below applies, and it costs nothing to establish.
Second: Do Not Disturb, which silences everything
This is the most common cause and the easiest to turn on by accident. Google documents it in its page on limiting interruptions with modes and Do Not Disturb: open Settings, tap Modes, then Do Not Disturb.
The fast check is the quick settings panel. Pull down from the top and look for the Do Not Disturb tile; if it is lit, that is your answer and you can stop here.
Modes are worth a second look because they can switch themselves on. A bedtime schedule, a driving mode or a calendar-linked mode will each silence the phone without anyone touching it.
Third: the app's own notification setting
If it is one app, this is where it lives. Google's page on controlling notifications on Android gives the path: open Settings, tap Notifications, then App notifications. Under Most recent you will find the apps that sent you something lately; tap the app and turn its notifications on.
Within an app there are usually categories, so an app can be allowed to notify you and still have the one category you care about switched off. A messaging app with chats muted and calls allowed looks broken and is working as configured.
Fourth: the battery setting that delays them
This one is the hardest to recognise because it does not block notifications, it delays them. If an app is set to Restricted background usage, Google warns that some apps might not work as expected and some notifications might be delayed.
A notification that arrives in a batch hours later, often when you unlock the phone, is this and not a notification setting. The fix is to move that app from Restricted to Optimized.
If the menu is not where this says
Samsung puts the equivalent under Settings, then Notifications, then App notifications, and keeps Do Not Disturb in the same Notifications screen rather than under Modes. On older Android the path was Settings, then Apps and notifications. The quick settings tile is the one part that works the same almost everywhere.
What none of this covers
An app that is signed out, or one whose own in-app notification switch is off, will stay silent no matter what the system says. So will a phone with no data connection in the background. If all four checks above pass and one app is still quiet, the next place to look is inside that app and not in Settings.
If notifications broke the same week an update landed, that timing is worth taking seriously rather than treating as coincidence. A Pixel update that broke the lock screen is a recent case of exactly that, and the first step there is also to find out whether it is you or everyone.
Last updated October 4, 2026