I am assuming that your keyboard does not work when you switch it on, is this correct?
Searching online, your tablet mentions that you can connect a Bluetooth keyboard to it. As they are not shown as being supplied as standard with a NuVision TM1088 tablet, is this cover with keyboard an after market accessory to your tablet? Is there a make or model number on the keyboard?
How do you normally charge the batteries in the keyboard? Do you have to plug in a separate charger for the keyboard to charge?
If you don't plug in a separate charger then perhaps the keyboard uses standard batteries that cannot be recharged and they have gone flat.
Does the keyboard have a battery compartment that you can check to see if there are any batteries in it? You may have to remove the keyboard from the cover to check it underneath and see if there is one there.
If so you can check the specifications of the batteries by what is written on them and then try replacing them with new identical types and see if the keyboard now works. Ensure that you insert the new batteries the correct way.