If my father told me to do something that I do not think is halaal or haraam, what should I do? For example, if he tells me to help him to bring a table for the television when the television may be used for both halaal and haraam?.
Television, as you say, may be used for both halaal and haraam purposes. If your father only uses it to watch permissible things, there is nothing wrong with helping him to carry it or to carry something to put it on; rather that is helping him in doing something good and you have to obey him if he tells you to do that.
But if he is using it to watch things that are haraam, then it is not permissible for you to help him in any way, not by turning the TV on, or by carrying it or carrying something to put it on, because Allah, may He be exalted, says (interpretation of the meaning):
“Help you one another in Al‑Birr and At‑Taqwa (virtue, righteousness and piety); but do not help one another in sin and transgression. And fear Allaah. Verily, Allaah is Severe in punishment”
And it is not permissible to obey him even if he orders you to do that, because the Prophet (blessings and peace of Allah be upon him) said: “There is no obedience if it involves disobedience towards Allaah; obedience is only in that which is right and proper.”
Narrated by al-Bukhaari, 7257; Muslim, 1840
In that case you should advise him kindly and gently, with wisdom and beautiful preaching.
If he uses it for both halaal and haraam purposes, there is nothing wrong with helping him to move something to put it on, so long as you do not know that he is going to watch something haraam at that time.
We ask Allah, may He be exalted, to help you to obey Him and to help you to honour your parents and treat them kindly.
And Allah knows best.