Recommendation Letters

[accessnash]

I'm starting to gather my LoRs and already feeling nervous about it. Have a few questions about the etiquette.

I emailed a professor in whose subject I got an A to see if I could set up a meeting for a LoR. He hasn't responded yet. I understand that some people say one should always ask directly in person. I'm willing to do that, but turning up at their office without an appointment might seem bothersome. Hence I emailed first. Now what do I do? Follow up by email again? Do Profs really miss some emails or is this a convenient way of saying No?

I'm currently in another class in which I've been doing fine. Would it be ok to ask the professor right after class or is it better to set up a meeting by email first? I was wondering if this prof also doesn't want to write a LoR but might feel uncomfortable in  saying so directly. 

I had given up a decent paying job to pursue a PhD and I don't have any plan B. I hadn't factored in the fact that I might not be able to apply due to lack of 3 LoRs.....I'm starting to feel a little depressed as the deadlines are coming closer. Just graduating with a MS would do me no good. Are there other options to get into a decent school without LoR?