Have had this happen to me, I can probably tell you the full story. If you forget or neglect to pay your domain registration, which can happen if the emails go into the junk folder or whatever, you site goes into limbo for about 3 months, and if you do not monitor the availability, almost on an hourly basis, when it is re-released, you get these site jumpers/claim jumpers who monitor well known sites and wait until it is reissued, ant then who come in and claim the site with a view of selling it back to you for an exorbitant amount.
Quite often the best way forward is to just rename your site, into a new sub-domain or whatever.
Edited By Alan Johnson 6 on 29/08/2011 09:38:04