this happened to me when i downloaded beta 9 i think it was.
Try going to Start -> All programs -> PostgreSQL -> Stop service
Then Start -> All programs -> PostgreSQL -> Start service
If this doesn't work, export all your hands from your database (i think its export, someone needs to back me up on that though, the one you use to put all hh back to your hard drive?)
If neither of these work, post your problem on this forum
(Beware, i'm not sure if i'm allowed to post that link so it may be removed by a mod, if so pm me and ill pm you back with the link)
Hope you get it working