This will be short and sweet for all my friends that have had problems with a “hacked” twitter account.
If your account has been sending DMs to your followers and/or tweeting without your permission, the security of your account has been breached and there are TWO things you need to do to address the problem:
1. You need to change your Twitter password. This is the obvious one, but still important. It is also important that the password you change to is complicated enough to prevent further problems. Get tips and test the strength of your new password before changing it on Twitter.
2. You need to revoke privileges from rogue applications. This is the one that many people miss. Applications that have access to your Twitter account can wreak all sorts of havoc even after you’ve changed your password. Revoke access to malicious applications.
For tips on how to keep your account secure, visit Twitter’s article on safe tweeting.