Hi Deepika, you can actually travel to Ladakh round the year, but you can not take the roadtrip to Ladakh. The roads are almost closed now from Manali side as the high passes have received snow. It is however still open from the Srinagar side, but not for long you. If you want to do the roadtrip the road will open only next year after June. Also, if you just want to enjoy Ladakh you can fly anytime of the year, In December everything will be under the blanket of snow and it will be very cold
Best time is from May to September, as in winter roads can get closed due to snowfall. I won't suggest ladakh in December unless you are specifically looking for thrill, however you can check chaddar trek in zanskar Valley.
Yes dec is best time to have snow view and enjoy extreme winters. If u travelling in the month of dec thn btr fly to Leh, ladakh. Road trip would be hard esp when u travelling all alone. Manali Leh route is almost blocked n upto dec u won't be able to go smoothly via Kashmir as well.