Playing video from computer to TV and can't get sound back

I have a Dell laptop running Windows 7. LG HD widescreen TV.

I connected my computer to the TV last night with an HDMI cable and played a couple of video clips on the TV and everything worked fine (including sound playing through the TV speakers). After finishing, I just unplugged the HDMI cable and turned both off.

Today, I went to use my computer and found the sound not working. I looked in the sound mixer and saw that it was trying to play sound through the HDMI port so I disabled it and sound started playing fine through the computer speakers again.

Later, I plugged the computer back into the TV but when I went to play a video the sound didn't feed to the TV and kept coming out of the computer speakers. I went everywhere I could find in the Sound settings on the computer and cannot find that HDMI option to enable it again.

Any suggestions on how I get to that setting? I know it's just a matter of reconfiguring or enabling that port or driver, but I just can't find it.

Thanks!