How do I reset my message counter to clear, or zero?

From BlackBerryFAQ

If you have an errant voicemail waiting icon on your homescreen:

• Call your voicemail and clear the message.

• Call your BB from another line and leave a message. From you BB, call your voicemail and clear and delete your messages.

• If the above fails, pull your battery to reset and reboot your BlackBerry.

If you have a rogue New Message icon on your Homescreen, or a negative count (-1), any one of these solutions could clear it, or reset it to zero:

Try these options:

• Hard Reset the BlackBerry by pulling battery while powered and reboot;

• View Messages > Saved Messages;

• View Messages > View Folders, check each folder (missed calls, SMS in and out boxes, MMS in and out boxes, Saved, browser, phone logs etc);

• Scroll to top of message folder, over the date heading, click or press menu to MARK PRIOR OPEN;

• Change your theme and see if it persists, and change back to your desired theme. (Options > Theme > select.)

• Wipe and reload your OS.