Receiving SMS using GSM SIM900

This is the code I use for receiving SMS and act accordingly , but when compiled I get an error saying "
sketch_apr20a.ino:1:23: error: SIMCOM900.h: No such file or directory
sketch_apr20a.ino:5:17: error: sms.h: No such file or directory
sketch_apr20a:7: error: 'SMSGSM' does not name a type
sketch_apr20a.ino: In function 'void setup()':
sketch_apr20a:23: error: 'gsm' was not declared in this scope
sketch_apr20a.ino: In function 'void loop()':
sketch_apr20a:35: error: 'sms' was not declared in this scope
sketch_apr20a:35: error: 'SMS_UNREAD' was not declared in this scope
"

Even if I add libraries I found over the internet , the same error occurs. Does anyone has links for sms.h and sim900.h ? or how do i rectify the errors?

#include "SIM900.h"

#include <SoftwareSerial.h>

#include "sms.h"

SMSGSM sms;

char number[]="97********";

char message[180];

char pos;

char *p;

void setup()

{

Serial.begin(9600);

if (gsm.begin(2400))

Serial.println("\nstatus=READY");

else Serial.println("\nstatus=IDLE");

};

void loop()

{

pos=sms.IsSMSPresent(SMS_UNREAD);

Serial.println((int)pos);

if((int)pos>0&&(int)pos<=20){

Serial.print("NEW MESSAGE, POS=");

Serial.println((int)pos);

message[0]='\0';

sms.GetSMS((int)pos,number,message,180);

p=strstr(message,"testpwd");

if(p){

Serial.println("PSWD OK");

p=strstr(message,"LEDON");

if(p){

Serial.println("LED ON");

digitalWrite(13,HIGH);

}

else{

p=strstr(message,"LEDOFF");

if(p){

Serial.println("LED OFF");

digitalWrite(13,LOW);

}

}

}

sms.DeleteSMS((int)pos);

}

delay(5000);

};

Even if I add libraries I found over the internet , the same error occurs.

Not it you install them correctly and restart the IDE. Since you haven't said what libraries you installed, where you installed them, and whether or not you restarted the IDE, you are on your own.

PS: That is NOT the way to post code!