You could try a hard reset to see if this resolves the problem, in case it is corrupted software that is the cause.
Here is a link that shows how to do it.
Before you perform the hard reset, ''backup the tablet using the tablet's backup feature as a hard reset will erase all your data and downloaded apps. It will restore the tablet to its' factory default condition. Also, remove the external SD Card (if any installed) and ensure that the battery is fully charged and that the charger is not connected when performing the hard reset.
When the reset is completed, (be patient it takes a little while), test the speakers to see if they now work.
If they still don't work it seems as though you have no option other than to open the tablet and inspect the speakers etc.
Here is a link to the Ifixit repair guide for the speakers in the tablet.
Verizon Ellipsis 7 Speaker Replacement
If they work then restore the tablet using the tablet's restore feature using the backup that you made before.
When it is restored, test the speakers again.
If they still work then the reset has fixed the problem.
If they stop working again, then perhaps a downloaded app is the cause of the problem. The trick is to find out which one. You will have to uninstall each downloaded app, one by one, and test the speakers between each uninstall to see which one is the cause.