Problem with tv signal , can some one help please ?

i have just bought a new 16 inch alba telivision from argos on tuesday . i managed to get it set up that evening with all my channels working perfectly . it has a dvd player inside it so i watched a dvd last night after that i could not get any of my channels back i could only watch itv1 but that was all fuzzy .this morning i tryed it again and i can only get all bbc channels i keep searching for other channels but it wont work . i live in the southwest , please help xx