If you post the TV model number it may help folk to answer your question.
On older Sony's they loved putting symbols on the handsets for tuning. Assuming you have the remote control, look for a shift button (arrow up), which may need to be held down at same time as another button, eg. triangle.
Very long shot...They also brought out some old models with reversable remotes, ie. tuning is on the reverse of handset. (press clips on each side and remote slides out of holder).
Cobweb
February 2007