I am not so sure that it is too late to get the D.A. to demand restitution. Up until the sentencing, the judge retains the power to disapprove the plea bargain. If you contact both the prosecutor and probation dept (put the case number and the next court date on all correspondence) and send them the documentary verification of your expenses due to this crime, the judge might well threaten to disapprove the deal unless the defendant agrees to add restitution to the conditions of probation. I suggest you send these letters by certified mail. Mr. Dane's suggestion about victim witness assistance is also a good one. The D.A. should have contacted you to ask about restitution, so they dropped the ball, but forget suing and just do the leg work your self to have this person ordered to pay you to avoid prison. Good luck.
You can sue anybody but if you sue the DA and the court you will lose. You won't even get to first base. Judges and prosecutors have immunity for what they do so forget it. Have you thought a civil suit against the person who assaulted you?
Well, you can always complain as we, as members of any state's bar, always adhere to a respective state's rules, ethics and procedure. Of course, since a DA is a county/state employee, I trust they have plenty of bosses.
As far as suing a prosecutor, the simple answer is no because, as a rule, they are immuned from civil suits if they are acting as a prosecutor when the decision is made to file, seek restitution, etc. While the act may be forgetful or even negligence, it does not make the prosecutor liable for your money damages. You would have to find that the prosecutor acted criminally in order to find any possible liability.
Of course, nothing says you cannot sue the defendant in civil court for money damages to make you whole, and since it is civil matter - double jeopardy cannot and will not attach.
In any criminal case, restitution will be part of the sentence. You're saying the DA hasn't demanded restitution. They can't at this point.
Contact the victim advocate in your county. Each county has a victim/witness assistance program. Let them know that you want to be notified of any court dates and that you have suffered monetary loss as a result of this case. They can assist you in filing any paperwork necessary to get the information about your loss to the DA and judge.