I own a 2005 hyundai sonata gls and would like to

Usually, if it is equiped with this filter, it's behind the glove box.

yeah it has a cabin air filter and should be fairly easy to replace.You have to take out the glove box and its behind it.First take out the skrews for the glove box door.Open it and you will see them.Then remove all the remaining skrews that holds the interior of the box and remove it.There will be two philips head skrews up on the top,remove those and then push downward on the acces door.once you open it then just remove the filter and reverse the process.Good luck!