All shards remain in unassigned state after upgrading elasticsearch


I upgraded my elasticsearch setup from elasticsearch-1.4.1-1 to elasticsearch-1.7.0

Before upgrade, the system health was green. After upgrade, all the shards have gone to unassigned state.
So I again uninstalled elasticsearch1.7 and installed elasticsearch 1.4.1-1 again.

Still the health state is not changing to green.
There is no indication of problem in the logs.

Following is the health status of elasticsearch.
"cluster_name" : "ms2_stage_elk",
"status" : "red",
"timed_out" : false,
"number_of_nodes" : 1,
"number_of_data_nodes" : 1,
"active_primary_shards" : 0,
"active_shards" : 0,
"relocating_shards" : 0,
"initializing_shards" : 0,
"unassigned_shards" : 269

Please help.

Is there anything interesting in the ES log file?