Use multiple options in if condition

if ( request.indexOf("LEDON") > 0 ) { digitalWrite(LED_Pin, HIGH);
dealy(60000);
digitalWrite(LED_Pin, LOW);}

this does not work
i tired making a function
void led1()
{
digitalWrite(LED_Pin, HIGH);
dealy(60000);
digitalWrite(LED_Pin, LOW);
}

and using like this
if ( request.indexOf("LEDON") > 0 ) { led1();
}

however when i use only i conditon in if statement it works fine
Iw ant to know is there any way to blink led after evaluating if condition

If that string is the first thing in you request variable, indexOf() will return 0 since that is the starting location. It returns -1 if not found.

Also, please read the sticky post at the top of the forum about how to properly post your code with code tags. It helps people help you.

Full code

#include <ESP8266WiFi.h>
const char WiFiPassword[] = "12345678";
const char AP_NameChar[] = "LEDControl" ;

WiFiServer server(80);

String header = "HTTP/1.1 200 OK\r\nContent-Type: text/html\r\n\r\n";
String html_1 = "LED Control

LED Control

";
String html_2 = "
";
String html_3 = "
";
String html_4 = "
";
String html_5 = "
";
String html_6 = "
";
String html_7 = "
";
String html_8 = "
";

String request = "";
int LED_Pin = D1;

void setup()
{
pinMode(LED_Pin, OUTPUT);

boolean conn = WiFi.softAP(AP_NameChar, WiFiPassword);
server.begin();

} // void setup()

void loop()
{

// Check if a client has connected
WiFiClient client = server.available();
if (!client) { return; }

// Read the first line of the request
request = client.readStringUntil('\r');
if ( request.indexOf("LEDON") > 0 ) { digitalWrite(LED_Pin, HIGH);
dealy(60000);
digitalWrite(LED_Pin, LOW);}
else if ( request.indexOf("LEDOFF") > 0 ) { digitalWrite(LED_Pin, LOW); }

else if ( request.indexOf("LEDON2") > 0 ) { digitalWrite(LED_Pin, HIGH);
dealy(120000);
digitalWrite(LED_Pin, LOW);}

else if ( request.indexOf("LEDOFF2") > 0 ) { digitalWrite(LED_Pin, LOW); }

else if ( request.indexOf("LEDON3") > 0 ) { digitalWrite(LED_Pin, HIGH);
dealy(180000);
digitalWrite(LED_Pin, LOW);}
if ( request.indexOf("LEDOFF3") > 0 ) { digitalWrite(LED_Pin, LOW); }

client.flush();

client.print( header );
client.print( html_1 );
client.print( html_2 );
client.print( html_3 );
client.print( html_4);

client.print( html_5 );
client.print( html_6 );
client.print( html_7);
client.print( html_8);

delay(5);
// The client will actually be disconnected when the function returns and 'client' object is detroyed

} // void loop()

dealy(180000);Really?

Please remember to use code tags when posting code

Does your code have
pinMode (LED_PIN, OUTPUT);
in setup()?

This line
dealy(60000);
(if delay is spelled correctly)
will turn on the LED for 60 seconds assuming you have it wired correctly:
LED_PIN to LED anode, cathode to resistor, resistor to Gnd.
Or assign pin 13 to LED_PIN and use the onboard "L" LED.

If you want to blink, then add a little for loop:

 if       ( request.indexOf("LEDON") > 0 )  { 
  for (x =0; x < 10; x=x+1){
   digitalWrite(LED_Pin, HIGH);
   delay(100);
   digitalWrite(LED_Pin, LOW);
   delay(100);
   }
}

That should blink it on/off 10 times, taking 2 seconds total.

on the ESP8266 please use the ESP8266Webserver for your http server.
The IDE example ESP8266Webserver | HelloServer gives you a first howto.

Parameters can be retrieved very easy with these three methods:
const String& arg(const String& name) const; // get request argument value by name
const String& arg(int i) const; // get request argument value by number
const String& argName(int i) const; // get request argument name by number

see the description on: Arduino/libraries/ESP8266WebServer at master · esp8266/Arduino · GitHub