Can't hear Wavepad playback

[strugglingwithwavepad]

I just made some recordings and at first could hear the playback. Now I cannot hear anything however I can see that the recordings were made. I am using Windows 7 and think somehow one of my settings was altered so it' mute. The mute button is not on and I am baffled by how this happened. I did not change any setting on my computer. It's my first time using this software. Any thoughts? Thanks.