N1Q1 queries not woking

Yes,meta is working.
How can we find which indexes is working or not working?

How many indexes you have on the bucket that not working.
Did SELECT META().id FROM {bucket}; is working? If not drop the primary index and retry

Yes,meta is working.
How can we find which indexes is working or not working?

Couchbase version? What ever the META().id value you got use that in the following query and see if that works.
SELECT * FROM {bucket} USE KEYS ["…"];
Also try SELECT * FROM {working bucket} LIMIT 10;
Also post exact query that not working with the EXPLAIN plan

we changed the CouchBaseNetClient from 2.4.7 to 2.4.8. things started working. I think the issue was with the dll version.Now the issue is solved thanks for the support.