I have a digihome tv, keepsgoing on and off, I have no control over it. when it is on the sound is from a different channel to what is on screen. nothing I do changes it. is there something I can do?

return for replacement or repair if try to repair or tinker with will void any warranty or return policy

You might consider buying a new one at:
DIGIHOME 22784wd TV NEW replacement remote control
or:
Digihome TV Projector Parts

Sure are you using a preamp component system or do you want to play it on the tv if you do have a pre amp run the RCA cables to sterio input on amp or aux then in the setting of the amp go into sound and put the aux to 6.1 also remember that to use audio out on your tv

sound no picture

have the wires right in the back of the TV, or unplug everything and start over from the get go.

is this happened either watching a tv channel or even watching dvd movies?. and then does the display only white screen or a totally black screen?.

sounds like time for a new unit

Can you please check the operation manual and the conditions mentioned in input for view in 3D, and check whether these are met?

Set up should be quite straightforward assuming you have all the bits.
You will need

1. a standard co-axial aerial lead from your TV antenna to the female socket on the Freeview Box
2. A scart to scart lead to connect the Freeview box (tv out socket) to the television.

If you wish to connect a video recorder or other equipment you may also need a second coaxial lead (male to female) for the RF through socket to connect to the aerial in socket on the video recorder.
If your TV does not have a scart socket you can connect the scart lead to the scart socket on a video recorder and then use the normal method of watching videos to view the Freeview TV pictures (here you may need to press the PAUSE button on your video recorder to prevent it going back into standby-mode after a few minutes).
Simply connect the box to your TV, turn on the power and the auto channel-scan will immediately detect and install all available channels.
If the Freeview box has been previously used in a different location / with a different TV transmitter you may need to re-tune it. Press the menu button on the remote control, scroll through the menu to set-up. Follow on screen prompts.

On your remote control, press 'menu'.
Then select 'set up' on the screen.
Then select 'Installation' on the screen.
Then select 'Automatic channel scan' on the screen.
The box should then scan for all channels, and with luck BBC will be included. If not, please repost. Some older Digihome PVR80s can't cope with the new multiplexing standard employed by digital freeview.