There's no way to do this, as someone else now owns the mailserver and you have no access (unless I misunderstood your post and you do have access to your old email account).
The only way to do this would be to contact the owner of the domain that your email account was on and request that they set up a forwarder. It's unlikely that any large business would bother, unless you happen to speak with the right guy or the admin is in a very giving mood.
There's no third-party that can intercept emails from another server and forward them for you, unless you had access to that server/account.
Looks like your 'up the creek'.