BBC channels lost after retuning ?

After an onscreen message telling me to retune I did . I now have completely lost BBC1 and 2 -- they are not even listed . I am not at all technlogy clever so can someone PLEASE tell me simply what to do now .I have a HUMAX PVR_9200TI . I have done the process of Initialising via Default Setting etc but everytime the search is completed then BBC is not found . Thanks so much for any help.