Problem re tuneing tv after switch over?

I have a freeview Samsung tv , decided since Virgin top box was becoming a bit dear to unplug and just use tv as when I bought it there were lots of freeview channels. However, when I go onto tv there is nothing but snowy picture tried re tuning but my remote says use D menu button but then tells you not available, can someone help me please and save me money at the same time , I did manage to store channels but it did not show up any found .. thank you