Headphone jack & internal speakers not recognized

Yesterday I plugged some headphones into the headphone jack on my MacBook Pro. Everything worked fine until I unplugged them. When the headphones were unplugged, the audio stopped playing and the volume controls were unresponsive. The internal speakers were not showing up in System Preferences. At this time, there was a red light in the headphone jack. To fix this, I simply blew into the headphone jack a few times. The light came on a few more times, but I just blew into the jack again to make it go away. The internal speakers were functioning. Maybe it was overly optimistic of me to think that this would be a real solution.

Today, neither the internal speakers nor the headphone jack are recognized. There is no red light in the headphone jack. I've tried two different sets of headphones (both of which work with other devices).

To summarize everything I've tried so far:

• Rebooting
• Updating software
• Blowing into headphone jack (no longer works)
• Gently wiggling headphones around in the jack
• Inserting headphones several times in an attempt to "reset" the jack

I have a 15' MacBook Pro (mid 2012) running OS X Yosemite 10.10.4. I've never had any problems with it before this.