If VoiceThread is not working for you please try the following solutions.

Note:  Chrome and FireFox are VT's recommended browsers.  Please use one of these two if you are having issues. 

First, make sure you've cleared out your browser cache - here are instructions - http://docs.voicethread.com/troubleshooting/clearing-the-browser-cache/

Next, clear our your cookies - http://docs.voicethread.com/troubleshooting/enabling-cookies/

Also, try another browser - If you are experiencing issues in one web browser and none of the solutions above help, try using VoiceThread in a different web browser. While all modern web browsers should work, Mozilla Firefox and Google Chrome are the best choices.

And lastly, add VoiceThread to your list of trusted sites (if you are using Internet Explorer). Here are the instructions:

a. Click the Tools button, and then click Internet options.
b. Click the Security tab.
c. Now click on Trusted sites and then click on the sites button.
d. Enter https://missouri.voicethread.com and click on Add.
e. When you are finished, click on Close.