mongodb replica set one shard cannot be restored

I have one MongoDB replica set with 3 shards, each shard has 1 Primary, 1 Secondary and 1 Arbiter.But before 1 month ago, the secondary node is down and can not be restored, then the primary is down also. I started the primary node with repair parameter and then it is repaired completely after 10 days. then I start the primary node with normal mode, but it always print “unable to reach primay for set shard3” and the serve port do not opened. How can I restore the shard3?