MIDI input suddenly stopped working

Hi All,
I’m new to Ardour. I installed debian with real time kernel and Jack Audio and Ardour.
Connected MIDI input to Ardour MIDI Capture on QjackCtl.
Went to Ardour.
Played a key on my digital keyboard.
Saw that ardour shows those notes being played.
Even recorded some and saved and exported it.
Closed Ardour.
It showed me a message about paying some donation.
I chose not to for now.
Opened ardour again! No midi input anymore!
Midi output still works. I can click on piano buttons on my track in Ardour and hear the sound on Piano.
Checked QJackCtl and system> midi_capture_1 is connected to ardour> midi/midi_in_1
What else should I check?
Thanks in advance.

Ok. The solution was so easy so I post it here for the record:
Restarted jack from qjackctl.
In Ardour there was a dialog saying that:
Audio backend is shutdown due to connection to Jack audio is disconnected.
Closed the dialog. Went to:
Window> Audio MIDI setup> Clicked on Connect to Jack.
Midi input is now working again (Have you tried turning it off and on again?!).

You do not need to use JACK unless you need/want to route audio+MIDI to/from other applications. If that’s not part of your workflow, then just stop JACK, tell Ardour to use it’s own ALSA audio/MIDI backend and make your life simpler.