How long is the F1 Visa stamp valid??

[visaquestions456]

I have applied for MBA program for Spring 2013 and got the visa stamping for 5 yrs. Unfortunately, I couldn't attend the university in Spring 2013 and deferred my admission to Fall 2013. I have the admission and I-20 for the new sem. My question is, is the F1 Visa stamp still valid for the Fall 2013 sem or do I need to go again for the stamping interview? I am confused and scared. Please help. Thank you!!

[kabkaba]

If you don't use the Visa for 5 months, it becomes void. It may still work, but if possible apply for the Visa again.