Windows 10 menu deleted after using Avast for the 1st time

Avast installed yesterday on laptop Dell XPS13 = Win10
After fater executed the full options to wash may laptop, I cannot start my laptop correctly (black screen…)
Usin ALT CTL DEL, il is possible to get the task manager and to launch Internet.
What to do to restore the start interface that has been removed by Avast…???

Well, solution found after a one day stress…
The use of the Windows task manager has been a key to be able to start “Explorer.be” which set my laptop (only for the session) in a normal way of work.

From this I have used System Mechanic" which found my laptop ready to use…What about this unrelevant diagnostic ???
Then I came back to Avast and I have seen it was possible to ‘undo’ requested registery removes.
Doing this, I can start again my laptop in a normal way.
What is the lesson learned? From my side, I know. What about Avast? I would be interested for some additional admin feedback.
That said, I keep my confidence for this tool as there is an undo option that have saved me.

From Belgium
Marc