What are my rights if I have been employed for 11 years and have applied for different job position in the department but I never get them?

I’m a 33 year old Hispanic male that is working for the sheriff department. I have been denied training and in some case, it requires a supervisor to write you a letter of recommendation but they refuse to write one for me so I can’t apply for the position. This last time I put in for a position at a clinic that used to employ us as a secondary employment but now are going to full time deputies. I had been working secondary employment at that clinic for around 6 years and know the job pretty good. There were 4 spots open and I didn't get any of the spots. One of the officers that got the spots has only been with the department for about 3 years.