How to get all the rows returned from the solr instead of getting only 10 rows?
You can define how many rows you want (see Pagination in SolrNet), but you can't get all documents. Solr is not a database. It doesn't make much sense to get all documents in Solr, if you feel you need it you might be using the wrong tool for the job.
This is also explained in detail in the Solr FAQ.