When the speakers do not seem to be working, usually the first thing you should check is that the volume is not turned all the way down. However, in the situation you described, the speakers stopped working suddenly. The issue is most likely a blown out speaker. A replacement speaker can be ordered here. For more information, see the Linsay F-7HD2CORE troubleshooting page.
The Linsay Tablet Model: F-7HD2CORE has a battery life of approximately 4 hours, so it is likely that you need to charge your device. Plug the tablet into a power source and allow it to charge, then attempt to turn on your device again. If your tablet's battery life becomes an issue, you may need to replace the battery. For more information, see our troubleshooting page.