Trouble with getting PhD recommendations - almost 60% turnover in faculty I just want to find out if this is normal, and see if anyone has any advice.

I recently decided to apply for a PhD program, and have been trying to get letters of recommendation. I first went with the professors I thought could give me the best recommendations because they knew me best, but when a week went by with no answer to my emails I did some research and found both were on leave (one with no estimated date of return). I decided to go through all the courses I'd taken, and organize the contact information for each professor. I found that, out of 12 different professors, only five are still active at the university. And wouldn't you know it, but none of the professors who gave me A's are active! (I know that grades aren't the most important thing in a letter of recommendation, I just thought it was an extra weird bit that all my B and B+ professors were still teaching). 

I worked full-time while getting my MA, and so I didn't go to office hours or schmooze with the professors before or after class (because I was coming straight from work with no time to spare, and after class I was either going right back to work or tired because it was late). I participated in classes, but I don't think any professor would say they know me well. Am I screwed as far as getting into a PhD program, even if I get recommendations about my excellent academic potential or whatever, if the letters aren't personal?
The most common and most valuable letters come from the professor(s) that were your academic advisor(s), or that otherwise directed or participated in your thesis work.

Not to be acerbic, but you made the mistake of treating your master's program as a place where you went to sit and look at powerpoint slides, and made use of your professors as if they were just there to read from powerpoint slides.  A typical response to a recommendation query from such a professor is likely to be "I don't think I'm a good person to write you a recommendation, because I will not be able to speak to your strengths and abilities."  

They say this to you because there is a well-established unwritten and unspoken protocol in PhD admissions, that of the "damning with faint praise" letter.  The committee reads that letter as "this professor either had nothing to say about the candidate, or chose not to say bad things about the candidate.  In either case, the professor had nothing GOOD to say about the candidate."

Beyond that...It is quite acceptable to ask an inactive professor (retired, on leave, etc.) to pen a recommendation.  It's entirely their prerogative whether to accommodate you though. Only your direct thesis advisor feels a burden of responsibility to write anything at all.