While we couldn't find the exact translation of the phrase "I miss you" in Cherokee, "I love you" is "Gvgeyu'i".
You can see a collection of useful phrases in Cherokee at Omniglot.
Cherokee (Tsalagi) is a Southern Iroquoian language spoken by around 22,500 people in North Carolina, Oklahoma and Arkansas.
The Cherokee syllabary was invented by George Guess/Gist, a.k.a. Chief Sequoyah, of the Cherokee, and was developed between 1809 and 1824. At first Sequoyah experimented with a writing system based on logograms, but found this cumbersome and unsuitable for Cherokee. He later developed a syllabary which was originally cursive and hand-written, but it was too difficult and expensive to produce a printed version, so he devised a new version with symbols based on letters from the Latin alphabet and Western numerals.
For more about Cherokee language, writing system and pronunciation, see Omniglot.