No response from Professor; how should I remind him about writing a recommendation for me?

I would send an email along these lines (taken from Cindy Au on Quora):

Dear Professor [Professor's name],

The deadline for submitting letter of recommendation for [name of program/ fellowship] is quickly approaching. I would like to inquire if there is still any document I can supply to make your writing easier in addition to what we discussed during office hours 2 weeks ago.

I understand that this is a very hectic time in the school year and thus can't thank you enough for your time and support.

Respectfully yours,

[Your name + ideally a link to some website containing your photo]

My experience was that professors tend to take long time to write recommendations and many of them just forget that you requested one. I would send him an email then visit him a few days later if he doesn't reply. You need to give many warnings and reminders or otherwise you will not get it.

Here is a useful and ethical problem free hack for emails in academia or any place where emails are used a lot:

Send your email at the right time - Not after dinner time so that next day when the person you are trying to contact opens the email in the morning and yours is under 1000 other emails... So I would say send it around the time where workday starts or around lunch. Then the chances of your email being in the top 10 and visible are much higher.