Sorry! I thought I had covered this but perhaps not directly. It's important so thanks for raising the issue.
First, get your owner title insurance policy in front of you. Make a copy of it to submit with the claim. If you can't find your policy, make a copy of your HUD-1 Settlement Statement. The HUD-1 is proof that you paid for an owner policy.
Look for the name and address of the actual title underwriter, not the agent. Some but not all policy jackets will have this information prominently posted, some will not. If you can't find it, look for a large office of the title underwriter in the closest metropolitan area. You can find it on-line if you Google their name.
Now, write a letter explaining the nature of the claim. Include all supporting data such as a letter you may have received from someone asking for money. Be specific and be sure to sign the letter.
Mail the letter along with supporting documentation and a copy of your policy to the title underwriter via certified mail. You want to get a prompt response and by sending it certified mail you will get their attention. BTW - send it to the attention of "claims department". that will get it to the proper person.
I suggest that you also call your title agent or attorney to let them know you are making a claim. WHY? Well, if they are responsible providers, they will likely jump on the issue and try to resolve it ASAP because they want to help you. Under no circumstances should you let them talk you out of making a formal claim. It's your right to do so and the sooner you get it started, the sooner you will get an answer.
Your responsiblity in any claim situation is to mitigate damages. That means you cannot delay contacting the title underwriter. Give them an opportunity to step up to the plate and defend you before you give anyone any money.
Once you have the signed receipt back from the post office confirming that your letter has arrived, if you haven't heard from anyone, follow-up with a phone call and find out who is assigned to your case.
If the claim is rejected and you feel the rejection is not fair, you can contact an attorney or the state attorney general or the state insurance commission for assistance.
There ARE circumstances that are NOT covered by title insurance and your title insurer should be able to clarify that in a way that you understand. IF, however, it's not clear and you think they are brushing you off, then pursue the matter.