The new forums are ready with new data. The old forum will be put into read-only soon, and any posts there won't make it across. I encourage the use of the new discourse, unless there happens to be some unexpected error.
You will need to reset passwords again-- alternatively you can log in with your github accounts and it should be linked with your forum account if they use the same email address.
If you use a different email address and you want to log in via github, reset your old password, log in and request an email change to your githubs email then you will be able to log in through your github account.