Hi, Nisha!
You visit Sangla, Kalpa, and Chitkul on the planned dates in March. You can take an ordinary or a luxury bus from Delhi to Shimla. From Shimla, you can either board a government bus or hire a cab to Chitkul and then explore Sangla and Kalpa while returning from Chitkul. However, be prepared to face extreme cold conditions and carry enough woollens.
Hi nisha... my suggestion .. jn march there will be very cold specially sangla and chitkul please try in april it very nice .. you can take direct bus from ISBT kashmiri gate to Sangla or To Shimla than take another bus from Shimla to Reckongpeo ...