If you have, what were your stats (test scores, GPA) and/or the classes you took in high school, extracurriculars, etc? Or, I guess, why do you think you were rejected?
I’m applying and although I have average/above average stats for the school, I’m still just a little worried that I’m going to get rejected (yknow, just because I haven’t been accepted yet).
Thanks 
MSU admits about 2/3rds of applicants and has a very large freshman class. That mean that student groups that typically score on the low side do not skew the average less so ‘average’ students are likely to be admitted. If you are in-state, average/above average in range, and don’t have red flags on your transcript (e.g. disciplinary problems, criminal convictions, poor recommendations etc.) I would not be concerned. I would get your application in as soon as possible since MSU has rolling admissions. During September response is relatively fast.
MSU admits to the university, and you must have a minimum college GPA to be admitted to certain competitive programs (e.g engineering, nursing, nuclear physics, etc.) Some people view this as a negative because there is no guarantee you will be able to matriculate in the program you want. but it may not be a concern for you. I would apply to a safety school as well.
As always, make sure your finances are in place. Completing the FASFA may be necessary for some work study jobs or scholarships, check with MSU.