What can I do one day before admissions deadline, if I believe my recommendation letter writer will not submit in time? One of my professors this term promised to write me a recommendation letter for grad school. However, tomorrow is the deadline and her letter is not on the application website. She really liked me, so it's probably a case of her forgetting about/misremembering the deadline.

However, I can't reach her via e-mail, and she's the kind of person who puts absolutely no information online (phone, travel plans, etc). Perhaps she's on some sort of trip to a conference or something. 

What can I do (with respect to the graduate programs I have applied to) to resolve this? Is there usually some sort of university policy regarding this situation? I really don't want to be unable to apply for grad school because a professor forgot to check her e-mail.

This situation is different from What can I do if a professor agreed to write a recommendation letter, but never sent it?, because in my situation the deadline has not yet passed.
I would try the following:


Contact the department(s) where you are applying, and ask them if they have received the letter.  (It's possible that they have received it, but for some reason it has not yet been logged in their online system.)  Explain that you would ask the professor herself but you cannot reach her.
If they say they have not received it, ask if they would be willing to keep your application under consideration, pending the arrival of the letter.  I don't know if this will help, but it's worth a try.
Contact the professor's department chair and see if he/she knows anything about the professor's whereabouts.  It is possible that something unusual has happened (e.g. she is in the hospital), in which case the chair may be able to write a note to the admission committee explaining the circumstances and asking for their patience.
If it seems that the letter may not be forthcoming within a few days, consider seeing if someone else can write you a letter.  Be sure to explain to them the circumstances, so they understand that it is urgent for reasons beyond your control.


Hopefully someone who has been on an admission committee will add an answer saying how they normally handle such situations (which must be rather common).