The only thing I can think of is that you may be using a different account than you did yesterday. As strange as that may sound, it does occur. If that is not what is happening you could send a message using this link: http://xenforo.com/contact/
Obviously you cannot do this if you cannot login to your customer account, but for other peoples reference that may notice this thread:
Q: I have an active customer license so why can't I post in or access attachments in the the Customer forums (Community Support, Resources, Add-ons and Modifications)?
A: Ensure you have associated your forum username in your customer account here. If you are already registered on the forum and use the same email address, the account will be synchronised automatically. It can take up to 10 minutes for the account to be processed.