So I was in your position almost four years ago. I was an old new grad, worked only 4 months in a new grad program before I realized I hated it, and then remained unemployed for over a year while actively looking for another job.
My advice is to expand your interests. Look for volunteer opportunities for nurses at free clinics. You probably have some in your area. This is a good source of references - people who are actively working with you, know who you are and your work ethic. I also second visiting your school/professors in person. This often is much more effective than a random email - they likely get dozens of these every week and can't always reply to them in a timely manner. You could also try adding them on LinkedIn, facebook, etc. (I'm still friends with all of my professors on FB - which is incredibly helpful for tracking them down in case you decide to go to grad school one day, btw.)
I would also look at other areas of nursing besides hospital nursing. I ended up getting a job in LTC/SNF which, while not ideal, was still a nursing job. It honestly isn't that bad and it paid more than my prior hospital nursing job. Also look at dialysis and home health. Once you finally do get that job, hold onto it for a least a year before you move on to something else.
Best of luck! Don't give up.