If you are unable to post on the new forums this is what I did.

1. Go to the top of the page and click on "Settings"

2. On that page scroll down until you see "My Account"

3. Click on "Edit Email & Password"

4. Make sure you correct email address is listed in "Edit Email Address(optional)"

5. In "Edit Password (optional)" type a new password

This worked for me I received a confirmation email.
I used a new password and did not try just using my normal forum password so not sure if that will work.
If anyone does try that please post a reply to let everyone know if you HAVE to change your password to a new one or not.