I could generally qualify someone based on sketchy info, but not all receptionists possess such amazing skills, so do your homework. And even if you know your brand of refrigerator, it's important to look at the filter itself as some brands make several types. Here's how you replace your refrigerator water filter:
http://www.amazon.com/Namtso-Refrigerator-Compatible-Whirlpool-W10295370A/dp/B01GE5MRKA?ie=UTF8&keywords=Refrigerator+Water+Filters ，
For the water filter DA29-00020B like the one picture above left, rotate the cap counterclockwise until its vertical pull the cap and filter cartridge out through the base grille. Push the new filter cartridge into the base grille until it stops with the cap in the vertical position. Rotate the cartridge cap clockwise to a horizontal position.
http://www.amazon.com/Namtso-Refrigerator-Compatible-Whirlpool-W10186667/dp/B01GHOG0BK/ie=UTF8?m=A3PRXLIP2OH339&keywords=water+filter+4396710 ，
For the filters like those on the above right, press the eject button and pull the cap straight out. Don't twist the cap or it will detach from the filter, and you'll have to put the cap back on and try again the way I told you to in the first place. Got it? OK. Push the new filter into the opening in the base grille. The button will pop out when the filter is in place, but give the cap a tug to make sure.
http://green-blog.org/blogs/entry/1339-how-to-replacement%C2%A0refrigerator-water-filters/ ，
This kind of filter, found in the upper right corner inside the refrigerator, is pretty easy to replace. Just turn the MWF water filter counterclockwise until it come out, drain it into the sink and trash it. Next, remove the seal from the new filter, insert the filter into the filter head and turn it clockwise until it stops. Easy.
http://www.amazon.com/shops/namtsostore ，
This filter to the right often sits in the back right of the fridge.