My windows could not play mpeg 4 or mp4 format..does a k lite codec could help?

You may want to install the codec pack from the link below, to ensure you have all the codecs required to run all video formats.

http://www.free-codecs.com/download/k_lite_codec_pack.htm

If this still doesn't help, you may need to reinstall your Windows Media Player (or other media software), and then apply the codec pack again.

Of course it will help. The problem of h.264 can't be played in the player mainly caused by loss of codec. Although the latest VLC version has implanted the codec, still you need to amend the VLC H.264 settings since it is not running by default. The guide will display how to play 264 files on VLC by going through detailed descriptions.

Source:How to Play H.264 File on VLC

Media Player Codec Pack is a piece of software on either a device or computer capable of encoding and/or decoding video and/or audio data from files, streams and broadcasts. The word Codec is a portmanteau of 'compressor-decompressor'. It supports almost every compression and file type used by modern video and audio files. With Meida Player Codec Pack installed, you can easily play any video in Windows Media Player. Windows Media Player won't play MP4 problem would never bother you again. You also don't need to ask people can Windows Media Player play MP4 files. You can also try Leawo Blu-ray Player which can support a lot of file formats including MP4.

A K-Lite codec might help...you can download it here: http://www.digital-digest.com/software/download.php?sid=1089&ssid=0&did=6

If that doesn't work I would try the VLC Player, it usually plays most videos. You can get that here: http://www.videolan.org/vlc/

Here are some step by step instructions:

First, download and start the install for the K-Lite Codecs Pack (click to download the latest version). K-Lite's install program might ask you to remove any existing codec and codec packs that might interfere with the set of software K-Lite will install - it is recommended that you follow K-Lite's advice and uninstall them. When you get to the "Select Components" section of the install, select "Profile 1: Default".

Scroll down a bit until you see the "H.264? option under "DirectShow video filters" section, select the checkbox and select "ffdshow" as the decoder to use.

Press "Next" again and then "Install" to start the installation. Once the installation finishes, you should now be able to play MP4/H.264 files (as well as MKV/H.264 files)

We will now download and install the latest ffdshow (click to download the latest version) to ensure the latest H.264 playback support. Go along with the install until you reach the "Select Additional Tasks" section of the install. Ensure "H.264 / AVC" option is selected. Continue on with the install using the default options (you might want to change the "Speaker Setup" option) and the latest ffdshow will be installed onto your system. Press "Finish" to close the installer and your MP4/H.264 files should now be ready to play - double click on them and they should open in Media Player Classic, ready for playback!

I hope this helps you.

Hello,
I think you should avoid using codec packs, just download and install a good player like one of these:

VLC media player
http://www.videolan.org/

KMPlayer
http://cdn.kmplayer.com/KMP/Download/kmp.exe

if you still can't play the files, try to install some of the most common codecs for mp4 files:
http://www.xvid.org/
http://www.divx.com/en/software/divx-plus/codec-pack
hope this helps, bye

Yes definately download and install it