The first thing is assault, the second thing; she wouldn't be eligible for a restraining order. You can't get one unless you have been threatened or stalked and you have sufficient proof. My question is, how is OP still in contact with an ex-coworker who has repeatedly asked her out and been rejected? If this makes her uncomfortable, maybe breaking contact would be a good start?

You can actually. 9 times out of 10, persistence isn't endearing, it's annoying. By the third time it starts getting creepy. If he can't accept a "No" for a date, what other "No's" is he going to ignore?

Uh, no, OP can DAMN well blame him for being persistent. If someone says "No," you should assume they mean "No." If you are rude, invasive, and selfish enough to ask again and they say "No," AGAIN, they definitely mean it, and you are being a creep. If you ask a THIRD time, you are just an asshole with boundary issues, who refuses to understand the meaning of "No," and sees people as objects rather than people. If you are turned down, you have BEEN TURNED DOWN, end of question. Don't "but" or "if" about it. If they change their mind THEY will ask YOU.

Not necessarily, just because someone says no to a date doesn't mean they will say no in the future. It all depends upon the time scale. Peoples feelings do change over time.

Yeah. That requires there to be a fundamental change in the relationship. You can't just wait a bit, with nothing changing between the two of you, and then saying, "How about now?"

I know many people who had no interest in their partners initially, some openly antagonistic to each other. Some of them eventually married. The smallest things can change anyone's opinion of someone else. Like the old saying, "Maybe they're not so bad after all"