Twitter has issued a warning that changing Username, Password or Email might result in some problems. They are investigating the problems reported by the users.

This is what Twitter says:

We’re currently researching reports from users who are locked out after trying to reset their passwords or change their email address or user names.  This seems to affect new users as well as long term users; we do not advise changing your user name, email address, or password at this time.  We will update Status with more news as it becomes available.

If you have any such problem, then follow this link at Twitter help. And remember not to change USERNAME, PASSWORD, and EMAIL until Twitter issues further notice. We will be continuously following the updates from Twitter and bring it here. Stay tuned.