You can request a copy of your file pursuant to the Illinois Personnel Records Review Act (820 ILCS 40/1, et seq.). If the employer fails to provide it, you can file a complaint with the Illinois Department of Labor (http://www.state.il.us/agency/idol/laws/law40.htm).
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Agreed with the other responses that you should find an experienced employment attorney. I recommend the Illinois Chapter of the National Employment Lawyers Association (www.nela-illinois.org). You may be able to find a good attorney in your area.
If the employer tries to use a change in policy to retroactively take away vacation time that has already been earned and accrued, then you may have a claim against the employer under the Illinois Wage Payment and Collection Act. However, if the employer has only changed the policy with respect to vacation time going forward, then it is unlikely that you would have a claim.