"Head piece broke and want to replace"に関する回答You can easily replace the headband with another. This is a link to the replacement guide for redoing the headband.
"Right side speaker has no sound"に関する回答This is the link to the troubleshooting page. According to it you may not being getting power to it or it may need to be replaced.
"Why will my device not turn on?"に関する回答There could be several reasons for this. The most likely cause could be a bad battery. Here is page that may be able to better answer your question.