(1)
There a many many different TVs that have DTV and ATV. The most likely fix will vary depending on which one you have.
For most TVs the user guide will contain the most likely fixes.
The most appropriate method of fixing your issue starts with reading the TV’s manual.
(2)
Once you have tried the user manual the next step is to use the internet search functions to search for your TV’s problem. You did not state the make or model of your TV in your very vague question. To search online it is similar to asking someone a question about your TV - you will need to include the make and/or model of your TV in the search.
(3)
Ask how to fix your TV on-line. To do this and raise the chance of getting a good answer you will need to state which TV you have and also give other details about what you have tried so far.
Your current question title is good but could be improved next time by including the make/model.
All the best of luck.
NS
October 2012