I created vfpage and it saved but no result displayed.My code given below:
VFpage:
<apex:page standardController="Account"  extensions="Searchclass" tabStyle="User">  
  <apex:form > 
  <apex:sectionHeader title="User Global Search" subtitle="Result"/> 
  <apex:pageBlock >
      <apex:pageBlockSection columns="1">
          <apex:pageBlockSectionItem >
              <label>Quick Search</label>
              <apex:outputPanel >
                  <apex:inputText value="{!searchstring}" label="Input"/>
                  <apex:commandButton value="Search records" action="{!search}" reRender="pgId" status="ajaxId"/>
                  &nbsp;<apex:actionStatus startText="Searching..." id="ajaxId"></apex:actionStatus>
              </apex:outputPanel>
          </apex:pageBlockSectionItem>
      </apex:pageBlockSection>
  </apex:pageBlock>
  
  
    
     
   <apex:pageBlock title="Search Account Result" >  
    <apex:pageblockTable value="{!acc}" var="a">  
      
     <apex:column headerValue="Name" >  
       <apex:outputlink >{!a.Name}</apex:outputlink>
     </apex:column> 
     <apex:column headerValue="Phone" >  
       <apex:outputlink >{!a.Phone}</apex:outputlink>
     </apex:column>
     
    </apex:pageBlockTable>     
   </apex:pageBlock>  

    <apex:pageBlock title="Search Contact Result" >  
    <apex:pageblockTable value="{!con}" var="c">  
     
     <apex:column headerValue="Name" >  
       <apex:outputlink >{!c.Name}</apex:outputlink>
     </apex:column> 
     <apex:column headerValue="Phone" >  
       <apex:outputlink >{!c.Phone}</apex:outputlink>
     </apex:column>
    
    </apex:pageBlockTable>     
   </apex:pageBlock>  
   
   
    <apex:pageBlock title="Search Opportunity Result" >  
    <apex:pageblockTable value="{!opty}" var="o">  
   
     <apex:column headerValue="Name" >  
       <apex:outputlink >{!o.Name}</apex:outputlink>
     </apex:column> 
     <apex:column headerValue="StageName" >  
       <apex:outputlink >{!o.StageName}</apex:outputlink>
     </apex:column>
     
    </apex:pageBlockTable>     
   </apex:pageBlock>  
  </apex:form>  
 </apex:page>

Extension class:
public with sharing class Searchclass {
  
   public list <Account> acc {get;set;}
   public list<Contact> con{get;set;}
   public list<Opportunity> opty{get;set;}
   public string searchstring {get;set;} 
   public string value1 {get;set;} 
   
   
    
   public Searchclass(ApexPages.StandardController controller) {
     
   }  
   public void search(){  
     if(searchstring != null && searchstring != '' ){  
     string searchquery='select Name, Phone from Account where Name like \'%'+searchstring+'%\'  Limit 10';  
     string searchquery1='select Name, Phone from Contact where Name like \'%'+searchstring+'%\'  Limit 10';
     string searchquery2='select Name, StageName from Opportunity where Name like \'%'+searchstring+'%\'  Limit 10';
     acc= Database.query(searchquery); 
     con= Database.query(searchquery1); 
     opty= Database.query(searchquery2); 
     }
     }
      }

Plz help