the name of the god who guarded the canopic jar?

This site names several goddesses who guarded the canopic box.

http://72.14.205.104/search?q=cache:ClLsCySlAL4J:www.metmuseum.org/explore/newegypt/htm/rs_glos.htm+god+guard+canopic&hl=en&ct=clnk&cd=3&gl=us&ie=UTF-8

This site names four gods who guarded the contents of canopic jars.

http://en.wikipedia.org/wiki/Canopic_jar

http://www.touregypt.net/featurestories/animalgods.htm

Baboon y`n - The dog-headed baboon was one of the manifestations of both Thoth, god of writing, and Khonsu, the youthful moon god. Both deities were related to the moon. Hapy, the son of Horus who guarded the canopic jars that held the lungs, had the head of a baboon. There was also a baboon god in the Early Dynastic period named Hedjwer, 'The Great White One', who became closely linked with Thoth. Sometimes Thoth was shown in baboon form, perched on top of the scales of judgement in the underworld.

Nephthys

The god typically associated with guarding the canopic jar in ancient Egyptian religion is Duamutef, who was one of the four Sons of Horus. Duamutef specifically guarded the jar that held the stomach of the deceased during the mummification process. To find this answer, you could have researched ancient Egyptian religion, specifically their practices related to mummification and the role of the canopic jars. Additionally, looking up the Sons of Horus, who were believed to protect these jars, would also have led you to Duamutef.