I was accepted into a masters program. They said I am "mostly likely," to get a scholarship which will significantly reduce the tuition fees. Then, i got an email saying I was nominated for the scholarship. The only thing i needed to do was to accept the award through their website. I tried to log into the website but faced many technical problems. I contacted the IT department and they referrred to the admission office. The same lady with whom I had been in contact for a while emailed me that I had delayed accepting the award so I have been waitlisted and there is a minimum chance to get the scholarship and I should plan not receiving it. Time between the first notifying email and the last was not more than 48 hours.

Meanwhile, as soon as I was assured of the scholarship I declined better offers from other colleges.  I wanted to attend this college and was my top choice. I was processing for the I-20 so that before college starts I could go home. Now, my opt is about to expire and would not be able to pay full tuition. I do not know how to deal it. Suggestions please!

That's messed up man. The university shouldn't be doing that.
If I were you, I'd contact any professors I know at the university, or the program director of the program applied to, or the faculties that interviewed you. If the school is not too far from you, set up an appointment with one (or more) of the above mentioned people and go talk to them. If that's not possible, call someone at the school you've talked to before (could be the professor who interviewed you or some other faculty you know). If there was no interview and you haven't spoken to any faculty there, send an email to the program director stating your problem; don't go around circles - keep it straight and short.

Don't even communicate with admissions office staffs in matters like these, they'll be of no help.
Good luck.