When you turn the television on, the screen is blank except for the letters/words: VGA NO SIGNAL We called our cable company and all their suggestions did not work. Could you please assist? Thank you

Are you trying to watch tv or use it for the computer? The input or source selection is on VGA at the moment which is the 15 pin input at the rear and it is expecting your computer to be attached. If you are using it with your computer you need to set the resolution on the computer to match the monitor, if you are not then switch the input to TV or whatever you have connected.
If you want to watch cable then switch the input through all the choices until you see a picture. Make sure the cable box is plugged in and powered on. The source or input button is below the number 9 on the remote, SOURCE: Press to select the signal
source, such as TV, AV, S-Video,
Component 1, Component 2 or VGA.

If you don't have a manual to tell you how to switch inputs you should find one here:
http://www.retrevo.com/d/df/LCT2715.pdf?doc=6c86396a98e4090a2ceb3bbb2052f498&ts=1296001090219&rk=0.035132213070726115
if link does not work go to http://www.retrevo.com and search for it