24 carrot island
Use the crowbar.
the factory, get the crowbar to open the vent
Find the crowbar-like thingie.
Use the crowbar to open the sewage pipe tp enter the warehouse on 24 Carrot Island.
You use it to open the secret passageway all the way to the right of the factory.
You find Charlie's kitty.
The black cat on Spy Island is just decorative and not part of the game. The gray cat, Whiskers, on 24 carrot island, can get you a crowbar. (see related question)
You need to contact Poptropica, you can mail them.
A glitch has probably occurred, so log out, quit your browser, and log back in and start again. If that still doesn't work, you will probably have to restart the island.
To get the underground paper on Counterfeit Island in Poptropica, you need to go into the underground tunnels underneath the museum area. Look for a grate on the ground that you can pry open with the crowbar item. Once you open the grate, go down into the tunnels and follow the path to find the underground paper.
you need to win it
I am not sure, but the question "How do you beat Counterfit Island on Poptropica?" will tell you EVERYTHING you need to know about the island. Sorry!