Unable to search for a Special Character using query_string

Hi Developers,

I am getting zero data after querying for a special character. Can some one help me with this.
The query I am using is as follows.
"query_string" : {
"query" : ""+"",
"fields" : [ "__title" ],
"default_operator" : "and",
"allow_leading_wildcard" : true,
"boost" : 0.1,
"analyze_wildcard" : true
}