I have an appointment with her this evening. Haven't heard from her, no phone or hotel contact provided. Has not responded to email in 10 days. What would you do?

"A,

I haven't heard from you in 10 days. I hope everything is OK with you and we can still meet. I'm concerned that there may be some emergency. If I don't hear details from you x hours prior to our scheduled meeting, I will simply treat it as a NCNS and move on.

Hope you're OK,
Concernedclient"

Tell her that you are confirming the appointment and if you don't hear back in x number of hours you will have to cancel. Sort of late to do this because she could be travelling today. Many hotels have 3:00 pm - 4:00 pm checkin times.

STP is right: make other plans.

Hi Arielle:

Since you haven't responded in a week or so, I assume something has come up that conflicts with our appointment today.  Accordingly, I'll go ahead and make other plans.   I hope everything is well with you.

Concernedclient

Make it clear that youre OUT.  If you leave the door open, you might make other plans and then, suddenly, she reappears, and YOU'RE in a bind.  

her this afternoon and all was good. I have seen her a few times and she has allways been very responsive. Something tells me you did something to spook her.

You haven't heard from her in 10 days how do you know you had appointment? I think jung1 is right, you must have spooked her. She always confirms 12-24 hrs before so I'd move on. Also, if she didn't confirm with you and there's been no communication how is that a NCNS? Just sayin...

Ring her doorbell, then run.

Or leave a flaming bag od dog doo.

I would take no followup contact as a derfinite hint.

There is obviously a good reason why you haven't heard from her.