A couple of things could have happened. You dropped the device, thus breaking the digitizer which is the part of the device that registers touch, which means to fix it you must replace that part. Simply google your Tablet and "digitizer replacement" after and you can find several sources that will sell it for you and allow you to repair it yourself.
Another option is less likely which is the touch never worked at all. In which case it is what is called "defective" and should be covered under warranty provided it hasn't been ages since buying the device.
Moving on you could have dropped or hit the device just hard enough to unplug or jar the connector on the digitizer which would stop registering your touch.
If no damage has occurred and you never dropped the device, or loaned it to someone who may have dropped it, your best bet is to contact a repair store or the manufacturer themselves. Contacting the manufactures could be more expensive than a repair shop but you will get a new warranty and most of the time, phone support. However if damage has occurred then this is more likely a digitizer problem rather then a defective device. In which case you are not covered under regular warranties and would need to pay out of pocket to have it fixed.
Your biggest issue is finding out what caused the issue. As stated before if no damage was done, then send the device back because you are covered, however if this issue is because of your own doing, then you will need to repair the digitizer. Which can be done yourself or via repair shop.
Thanks to @Jayeff here is a link to the guide for your tablet. As stated it will allow you to take apart and diagnose the issue with the tablet. Either a simple loose connection, or replacing the digitizer the guide will solve your issue.
NuVision TM1088 Repair