Reformatted computer now lots of songs and vids wont play!!

I have downloaded all new codecs but lots of music videos and songs wont play and error just appear. Dont have a clue wot codecs i had but does any 1 know of a codec package which is good and covers everything but doesnt clutter the computer?

Thanks!

http://www.free-codecs.com/

i hav been to this site and got codecs but it hasnt fixed anything.

From that site download GSpot and Avicodec and open one video file with one of them is going to tell you what codecs you need and avicodec give you some links.A basic codecs collection is any pack you like,Xvid DivX and players like VLC and BSplayer.Also is a tool called Sherlock codec detective and this can tell you if you have any broken codecs.Next time when ask for help be more specific what codecs and what players you try and what error you get.