Who did you register the domain through? If it was a hosting company, who did they register it through? This will be the registrar mentioned in the details you will get from the sites mentioned by Synarch.
It will probably be godaddy.
If you are changing from one hosting company to another, have you already terminated your contract with the old hosting company? If you have, they probably abandoned control of the DNS records and decommissioned the server. Searches for the domain might then return the domain registrar, because the hosting company is no longer supplying an address for the domain.
The state of the server and the data it contained would then depend on the policies of that company.
If this is what has happened, You need to contact the old hosting company and find out what has happened and get the information you need to administer your domain details (you'll need this when setting up the DNS for the new server at the new hosting company).
If this is not the case then I don't know, maybe something broke somewhere.
All of that is conjecture based on my tenuous assumptions. Call your web host, ask them what they think is happening, don't make accusations, tell them what you saw, on what computer, where and when. You may be able to check their web site and see if they listed any service outages (I've had hosting companies disappear from the net for a few hours, their entire data centres falling off the net).