Unless you lease provides otherwise, the lease will continue running regardless of who owns the property. For example, if you signed the lease on June 1 and it's a 1 year lease, your lease runs until May 31. The new owner would have to abide by the terms and conditions of the existing lease.
As noted, if there was some provision in your lease saying that the lease could be terminated if the property were sold (usually there isn't), then your lease could be terminated upon sale.
Yes, you certainly should have been informed that the owner was trying to sell the property. But now the owner probably has painted himself into a corner. Having tenants with a valid lease in there--you--is going to make the house much more difficult to sell. As a result, the owner might want to buy you out of your lease. Or you might want to approach the owner and say: "You know, we have a current lease that runs until xxxx. That may make it very difficult to sell to someone else, since our lease will remain in effect until xxxx. But if you'd like us to move out sooner--maybe when you sell the house, maybe sooner--we'd be willing to consider allowing you to buy us out of our remaining lease."
See a lawyer for more information.
Hope that helps.