Conversation so far:
When did Garry Kasparov lose the tittle?
2000.
Who did he lose it to?
Kramnik.
What was the aftermath of him losing the title?
After losing the title, Kasparov won a series of major tournaments, and remained the top rated player in the world.
Did he ever won the title back?
CANNOTANSWER.
Are there any other interesting aspects about this article?
In 2001 he refused an invitation to the 2002 Dortmund Candidates Tournament for the Classical title.

Question: Why did he refuse the invitation?
Self-contained rewrite: Why did Garry Kaparov refuse the invitation to the 2002 Dortmund Candidates Tournament?