it's been several year since one.lv closed their service. If you are trying to use the route of getting access to your account containing bitcoin via the company behind the mail service, then i bet it's going to be impossible.
Without any private keys or seed phrases, then your Bitcoins are as good as gone.
I did a small search and this is what I got
Mail forwarding for One.lv website is disabled
February 7,2013
As of 31.01.2013 the social network One.lv has ceased its operation. Some Inbox.lv users used the services of One.lv mail service along with Inbox.lv and configured their mailboxes to forward incoming emails from Inbox.lv to One.lv.
On 31.01.2013 the administration of the One.lv portal deleted all mailboxes that were registered at One.lv social network and opted out of receiving incoming messages. To avoid possible technical problems and for users’ convenience, the administration of Inbox.lv automatically deactivated all forwarding to non-existing mailboxes at the One.lv domain.
Source:
https://company.inbox.lv/2013/02/inbox_post_60/?language=enForticom seems to be the company behind the email service
https://en.wikipedia.org/wiki/Forticom. Maybe you can try contacting them -
http://forticom.lv