Whilst an avast repair may well resolve the problem.
I would suggest before doing this you restart your system, if you see the Avast tray icon with an exclamation point, try opening the UI to identify what Shield, Component, that hasn't started. Right click on the tray icon and select About Avast > Components and see if you can find the one not running.
There have been occasions when a shield or component is slow to start.
You may also check the avastUI > Settings > General > Status Monitoring and check if a component that you aren't running has status monitoring enabled.