I am using a Dell inspiron 1464. Scroll lock function is enabled. I cant turn it off. Kindly guide me.

PUSH (Fn+F4) THIS SHOULD BE THE NUMBER LOCK KEY ON DELL

Turns on when the numeric keypad is enabled.
Turns on when the uppercase letter function is enabled.
Turns on when the scroll lock function is enabled.

scrolling is a function of the touchpad driver, try downloading it and reinstalling the driver.
support.dell.com is where you can find the driver

Those are Diagnostic indicators that point you to the possible cause. The padlocks will have a number ( Turns on when the numeric keypad is enabled.) or capital letter(Turns on when the uppercase letter function is enabled.) or arrow key(Turns on when the scroll lock function is enabled.).
According to those indicators you either have a bad memory module or your CPU (processor) is bad.

To enable or disable the touch pad, press the key on the function key row on the keyboard. It is next to the F12 Key.

Hope it helps! Good Luck!
CreativeTECH

You have 3 padlock LED's. They are as follows.
Turns on when the numeric keypad is enabled. Turns on when the uppercase letter function is enabled. Turns on when the scroll lock function is enabled.If you don't get a display when Windows tries to load then you probably have a video driver issue. Try to load Windows in safe mode by powering on the laptop and tapping the key. If it works then your video driver might be corrupted or your video circuit has a problem.

Try re-installing the Touchpad Driver in the Computer.

You can download the Touchpad Driver from here

download the latest drivers from dell.com

i cant if my mute botton it all was say mute of and i cant hear anything

Unlike previous models, The 1545 has no imbedded Numeric Keypad, so there is no NUMLOCK option.
For numerics, you will have to use the numbers above the QWERTY row.
SCROLL LOCK was also eliminated from the 1545 keyboard (Legacy item, seldom used)
If you need a numeric keypad and/or Scroll Lock, then an external keyboard may be an option.