no playback usb sound focusrite card

My usb focusrite sound card stop playing back with Ardour 5.12, other programs play sound but not ardour 5.12.In fact when Ardour is open no other program will play sound unless I close Ardour 5.12!?

Ardour 5.12 was working everytime I selected the alsa driver together with the usb focusrite sound card as input and output but now even if selected the same settings and started alsa driver there’s no sound playback at all, the meter shows sound been play but nothing can be heard.The usb focusrite sound card works with other programs but it stop working with ardour 5.12 at all.

Please join us on IRC so that we figure out what is wrong more efficiently than via a web forum. Links to a web-based IRC interface at the bottom of this (and every other) page.