Accidentally silenced the tracks


Am using audacity 2.0.4 and windows vista.
Was working on a project, wanted to silence a part of the track I was working on but believe I have accidentally silenced all the above tracks as well. I can see the wave patterns but they are grey now instead of blue and when playing I have no sound. I have saved the project so cannot go for ‘undo’.
How can I remove the silence from all those waves or do you think I have a different problem?
Thanks in advance for any reply.

I think that you may have accidentally clicked one of the “Solo” buttons.
The track Solo buttons allow you to listen to one track on its own by “muting” all of the other tracks.
See here for how track Solo and Mute buttons work:

The quick way to un-mute all tracks is to press Shift+Ctrl+U

Indeed, managed with the solo buttons to get the sound back. Thank you Steve!