Normally every key on a keyboard should trigger a sound. However, most electronic keyboards can shift the note values which are generated by their keys, either by a certain number of semitones, or by a certain number of octaves, or a combination of both. MIDI has "only" 128 different note values, which extend roughly one-and-a-half octaves below, and one-and-a-half octaves above, the 88 notes on a standard piano, as shown in the picture in this post:
https://www.keyboardforums.com/threads/help-out-a-novice-midi-korg-microstation.27312/#post-180207
Although the notes on a piano keyboard normally fall well within the range of possible MIDI note values, if you use octave-shifting, possibly combined with semitone-shifting (or transposing), you could conceivably shift the highest or lowest keys on the keyboard beyond the range of MIDI note values. However, the way this is typically handled by a keyboard is that any notes which go beyond the range of possible MIDI note values are octave-shifted up or down to keep them within the allowable range, such that the highest or lowest octave on the keyboard will trigger the same MIDI note values as the adjacent octave.
Also, every natural musical instrument (e.g., trumpet, tuba, flute, clarinet, harpsichord, xylophone, etc.) has a definite range of notes that it can play, and some tone generators might restrict the note ranges of specific instrument voices to the natural range of that instrument. However, this is more commonly seen in virtual instruments and sample libraries, whereas (as far as I know) electronic musical keyboards will usually go ahead and play notes that fall well outside the natural range of a particular instrument.
And finally, generally speaking there are two different types of voices on a MIDI-compatible keyboard-- melodic voices where each key plays a different note or sound frequency of a particular instrument sound, and kit voices where each key plays a different type of sound (e.g., different percussion instrument sounds, different types of sound effects, etc.). Kit voices usually have a more limited range than melodic voices-- i.e., they might extend a little bit beyond a 61-note keyboard, but typically will not span the full range of an 88-note keyboard.
Thus, if you're talking about the sounds played by the drum kits, it's normal that the highest keys don't play any sounds. But if you mean the melodic voices, then it could be that there's a problem with those keys on the keyboard, or that one of the situations described above is involved, or that you aren't able to hear the frequencies played by those notes. However, if it were an issue related to hearing loss then I would expect the sounds of the notes to fade out gradually, not abruptly from the B note to the C note following it.
If it's a brand new keyboard then I'd take it back to the store where you bought it so they can check it out while it's still under the manufacturer's warranty, just in case it does turn out to be a hardware problem of some kind.
