The speaker may need to be cleaned. To do this remove the faceplate off the device and get a toothbrush and scrub the back of the speaker. If that does not fix it try centering it over the speaker output on the device. If neither of these fixes work the speaker will need to be replaced.
Your battery may be damaged or no longer holding a charge. You will need to replace the battery in either case. Link: Ematic FunTab 2 Battery Replacement The motherboard may also be in need of replacing due to some damaged connections or other various reasons. Here is a link to replacing the motherboard Ematic FunTab 2 Motherboard Replacement
You might have a damaged charging port. If your charging port is intact and has little to no damage you will have to replace your battery. Here is a link to replacing the battery Ematic FunTab 2 Battery Replacement
You may have problems with either the screen or the battery. The simplest remedy is to replace the battery. If the battery is not the problem this screen will need replacing. Here is a link to the repair page Ematic FunTab 2 Battery Replacement
There are 3 solutions to this problem. 1. Your speaker could simply use cleaning. To clean just use a cotton swab and clean the speaker. 2. The speaker might be out of position. To reposition the speaker remove the faceplate of the device and line it up with the speaker slot. 3. If the first two fixes do not solve the problem you will need to replace the speaker.
Start by checking if your charging port is intact. If it is not the port may need to be replace. If the charging port is intact the battery will need to be replaced. Here is a link to the repair page Ematic FunTab 2 Battery Replacement