I was recently suspended from my job. I want to know if I have the right to obtain from my employer a written reason as to why I was suspended

I was going through some emotional problems (grief, depression) spoke with my boss who said I should go on FMLA which i agreed to. she then stated that another coworker informed her that i use crack and meth which is why i have not been as accountable at work (which is NOT true). i called this coworker several times to find out why said never got ahold of (i did in past have substance abuse history and previously shared with her). After calling her she called my boss who asked me to stop calling. I called boss who then informed me I am being suspended because of these accusations and an investigation is to be done. I want to know if i have a case...I also requested to have reason in writing and have been denied. All of my coworkers have been asked by the VP about me but he has not even contacted me. I told bosses numerous times about my emotional issues without any resolution...recently started seeing therapist and new medication given