I got slapped by a coworker,there were not witnesses, but the supervisor was there but she's Anna's friend ,I told her Ana just hit me,and Ana started yelling yes I hit her and what, I don't care, unfortunately I didn't call the police right away,I went later to let him know what happened, but he called my boss and Ana,I think the boss and Ana told him a different story, I tried to get a restraining order, at the hearing she said she hit me in self-defense because I was going to hit her first,she changed the whole story.after she hit me i could hit her back,but i didn't do it because i'm not a fighter ,but i didn't get the restraining order,but she got fired, and the district attorney already said,there is not enough evidence they won't press charges against her,I don't think is fair,I'm ok,she didn't hurt my eye so much,it was just a contusion, I went to the doctor the same day,that's not enough evidence. Another coworker was at the same time this happened, but the problem is she didn't see the right moment when she hit me,but Ana confessed what she that's not enough evidence.I was really depressed the first week after this happened and anxious too,I m not too bad now.
Unlikely that a civil action for personal injuries is worth pursuing against an unemployed co-worker but feel free to consult local personal injury counsel. Prosecutor/DA alone decides which cases to pursue criminally.
It is not you, as an individual that would press charges. It is the responsibility of the district attorney to bring charges against persons suspected of committing crimes. Since in your case you say that the DA has said there is not enough evidence and he will not press charges, charges obviously will not be brought at this time.
You couldn't press charges, even with witnesses. You make a police report, the police refer to the district attorney - that's the procedure. Suing an unemployed ex-coworker appears to be a waste of time.
You could try suing in small claims court, but it sounds like your damages are minimal, which means there isn't going to be much prospect for financial recovery. Also, it sounds like a "he said she said" situation, which means you could lose on liability since you bear the burden of proof. Best of luck to you.