I am trying to play a tune in my keyboard textbook and I am having trouble figuring out what the notes are for the lower clef and what octave they are in. Can someone help me with this please? Also can it be played on a keyboard with 76 keys?
It's pretty common to change the clef in piano music. In your case, the right hand has moved in the lower range of the piano, so it wouldn't be easy to read many ledger lines below the staff. That's why the person who wrote this sheet has changed the treble clef to the bass one.
You don't change octaves. The low B in the left hand is played in the octave it is written and the same goes for the high B on the right hand. Just read both hands as you would read the left one.
And yes you can play that on a 76 key keyboard.
It would be the B before the '1' on the pic above.