no digital signal on my DMTECH 17 LCD?

I have no digital signal on my DMTECH 17 LCD. The TV/DVB-T button has no effect when used on the remote. When entering the reset and eprom menu the DVBT is shown as OFF but I cannot find a way to change this to ON. The mdel number is LT17XTS. Please help as the analogue signal has now been turned off, so can only be used to watch DVD's