help... i have lost the pound sign. how do i retrieve it please?

Several possibilities:

1. Turn the keyboard over and rap sharply on the back several time all along the length. This may dislodge any crumbs that have gotten in there. If you haven't done this before, you may be surprised at the amount of junk that will come out.

2. Try the keyboard on another computer to see if it's defective or not.

3. Borrow a keyboard and see if the problem goes away.

Replace if necessary.