Since Kingfisher is facing financial problems, air transport has come to a halt in Himachal Pradesh. The airline was offering regular air services to Bhuntar (Kullu), Gaggal (Kangra) and Jubbarhatti (Shimla). Air India offers air services to Bhuntar (Kullu), but the service has been suspended. No other airlines offer regular air services to the state. So you have only one option left: road transport consisting of public and private buses and taxis.
For online bus booking, you can check the following websites: