How to improve ranking of a website again, after being penalized by Google?

[TGA123]

The ranking of our website has gone down in past 2 months. The reason,
I believe is that we had more than 300,000 spammy comments posted on it
(the website is based on wordpress) so Google treated it as
un-monitored forum and penalized. We have deleted the older comments
and new comments can no longer be posted. Need suggestions on what else
should we do to rank better. Any advice would be very welcome.

[KevinBudzynski]

As you already probably know, begin (or continue) the pursuit of valuable (high pr--or at least contextual relevant) inbound links.

This is one of the most important factors in getting back on top.