Sounds like the current track panel size might currently be too small to show the track input box (see image below).
So try to drag the lower and right edges of the track panel to make it bigger.
In general, it's also possible to access the input and record mode options via Right-Click on the Track Record Arm button.
Otherwise check which Track Layout is currently selected under 'Options > Layout > Track Panel' in order to rule out that it's perhaps set to a Track layout which doesn't have a track input selection box at all.