Unless you plan to take a flight to Leh or drive down in your own vehicle, there are buses plying to Leh from Srinagar and Manali. On the Manali-Leh route, overnight stops are made at Keylong by local HPTDC buses while there are shared taxis available which stop overnight at Sarchu (4253m). If you are travelling from Srinagar, the buses stop at Kargil while there is accommodation at Alchi and Lamayaru.
There are daily flights to Ladakh from Delhi, Jammu and Srinagar by Jet and Indian airlines. However, flights may be cancelled due to incremental weather.
Trains are only available till Jammu if you plan to go through the Srinagar-Leh route and till Pathankot for the Manali-Leh route. After that you can either fly or go by road to Ladakh.