Wrongful Termination Without Cause

I was terminated from my job a few days ago after 2 1/2 years of service. The reason that my employer gave me was that my skill set did not match the direction in which their IT Department was headed. Leading up till this point, I was given a commendation and a large bonus for my extradinary work a few months earlier (I never saw this coming). The problems started to arise when my new IT Manager came aborad. He constantly would berate my work and refer to me and other female staffers as "chicks". I went to my HR department to voice my concerns, but nothing was done resolve this issue and put me at ease. I was given 1 month severance pay, and was escorted out of the office, thus not being allowed to collect my personal belongings. What recourse do I have for a lawsuit and to collect my personal belongings. If this will help, I also reside and live in Washington, DC and my employer is in DC as well.
Thank you.