NO SOUND = WHYYYYY

Hi,

i have 8 sessions for a serie. work hard for 3 month. and now i start to have this bug i never had before : no sound at all.
i close a session a minute ago all was fine, reopen it and nothing is happening on my tracks.
there’s regions, data, all automations are ok but no audio activity on meters !
WHAT THE HELL !

… have to relaunch nuendo. but sometime twice !!