You have not provided enough information for an answer. For example, you have not explained what type of complaint you want to file. If it is based on discrimination, visit the EEOC's website for information about filing a charge and the time frames for each type of charge. You may also check with the Washington State Human Rights Commission's website for more information. Generally, for certain types of discrimination, you have to file an EEOC charge before filing a lawsuit.
You may also consider consulting an attorney licensed in Washington (I am only licensed in Arizona) for more information about your claims the timeliness. Good luck.
Mishka's suggestions is valid. It is impossible to say exactly how you should move forward, or even IF you should move forward based on the limited facts provided.
In general if you want to bring claims under federal laws (think Title VII anti-discrimination type laws), you must file an EEOC complaint before filing a lawsuit. Generally speaking there is no such requirement under Washington law.
In either event you should review the websites (EEOC and www.hum.wa.gov) to determine if you have a claim. Then I strongly recommend contacting an attorney before you file a complaint or a suit.
Best of luck.
It appears that you are a federal employee because you're asking about a 45-day deadline. In the non-federal sector, the deadline is 300 days. Plus, if you're not a federal employee, you have 3 years to sue for discrimination under Washington law.
Bottom line: you need to contact an employment lawyer for help.