I am a student and last year for whole year I didnot work (using my ssn). Do I still need to file taxes?

 yes you need to file taxes even if you dont owe anything. there a special form for international students, use that form.

deadline april 15 ho kyare, ahile samma chhai kasko k herdai baseko ni??

Contact international office in your school for more information.

If you have no income there is no need to file tax return

@Yuvaraj, dont give advice if you dont know what you are talking about. जे मन्मा आयो तेही guess हन्दिने? गजब्छबा !! 

@Chromatic, yes, you need to file taxes regardless of income.

@jai Nepal please provide your sources before making that kind of statement
You can go to the IRS website and review section on who needs to file taxes:
If your gross income as a resident or citizen is less than 9750 you do not have to file an income tax return.
As a non resident there are certain conditions when you will have to file 1040 NR even if you dont have income if you meet certain conditions: like : trade in the US etc. you can find this info in the instructions of 1040 NR
But if you are a student with no income no trade etc for the whole year there is no need to file income Tax return/1040 NR
International students can file form 8843 to show that you are exempt from consideration of resident alien for tax purposes. This is not a tax form and can be filled and mailed to IRS ( address will be on the form) and it is due June 17 2013 and not April 15 2013.
This is not necessarily a requirement but most people would file it otherwise theoretically irs can come after you and try to tax income from other countries that you may have like in Nepal by assuming you are a resident .

I have heard abt that too. Our international office conducts tax filling sessions for international students. One of the students had a federal return of less than $20 and the tax personal said if she does not want the $20 back, it is ok to not file the tax .