The place to start is by dealing with the current registrar - GoDaddy in this case. Email
abuse@godaddy.com and explain that you are the actual owner and forward bills that show you have been paying for the domain. It might also be an idea to send the previous WHOIS information too (below)
Inform them that you will be taking legal steps if necessary and that you would rather sort this out amicably. I have found most registrars very helpful in these circumstances.
If you do the above before getting a lawyer involved, it will make the lawyers job a lot easier.
--- Archive WHOIS ---
Registrant Contact Information:
Name: Susan Larson
Organization: Susan's Place Transgender Resources
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Email:
susan@susans.orgAdministrative Contact Information:
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Technical Contact Information:
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Information Updated: Mon, 5 Jan 2015 18:17:18 UTC