Looks like someone stole your "shellnew" entry for text files. Try diving in the registry, HKEY_CLASSES_ROOT, and find the ".txt" extension. Inside that key should be another key called "ShellNew". If it's not there, make one. Now stay over "ShellNew" and make a string called "NullFile". Leave it's value data blank. Restart just in case, and your missing Text Document should return... in theory.