"I've changed my cmos battery n still there is 5 beep sound."
Which, as you probably know, means an RTC (Real Time Clock failure) The CMOS battery is either absent or faulty.
I know you changed the battery, so its worth checking that you didn't insert the new one the wrong way up. Make sure it is seated probably as well. If that doesn't work, try another new battery. Make sure it is the correct type (almost always CR2032) and buy it from a different shop.