filled tax form as a resident American; however I am not american and I am here only for 9 months. What kind of difficulties I will have to face in future. I am here in f-1 status. Hoping for better suggestion.

First of all, F1 status isn't a Resident of USA. It's a non-immigrant visa,non-resident visa.

 Is it completely illegal?? what kind of consequences I have to face in future?? Plz help me..

Tera kya hoga kaliya? :)
So what was the purpose of filing the taxes and what have you done.
More details

 I asked my int adviser she told me that it is legal to file tax. If you are planning to be a PR here it is better to file a tax but as a student ( non resident). Even IRS wants us to file tax for thier record otherwise if you will be PR its gone be problem. we have to file a tax as a student.

It will be good to file tax for government refereea;l. But my question is while i was a student , I use my SS # to work in ocean city, which is not permit, will that be a problem in the future?

I am a US citizen, but my GF is in F1 status. She works in cash near our apartment gas station, how to file tax  ?

Subashini, what you are stating is totally wrong and doesn't make sense at all. Either you didn't understood what your international advisor told you. Consider these two diffeernet scenarios. Filing taxes is done with the IRS and maintainins status and abiding by the rules of your visa is another thing. Let's say you are working using SSN on F1 visa but didn't file taxes. That means you are voilating your visa by working when not authorized to work and you are voilationg federal law (not filing taxes when making income). 
They (USCIS) will surely look if you filed or paid taxes when you were required to, that will be important when they file for green card. 
But if you file taxes in F1 status, which you can't because you have to pass the residency test. But certain things like you make interest in your bank account, sell stocks and made money, received dividend, or stepiend income, those things should be reported by the party who withholds tax on your behalf and report it to the IRS. But that doesn't mean you have to file taxes.
As you have already filed taxes, the best thing to do would be to do nothing and hope that they don't get you in trouble. 
IRS do have systems that can verify your social security with the social security administration, but they wouldn't have anything to verify wethere you are eligible to work or not. Immigration/USCIS can verify if someone is working illegally or not with enquiring with IRS, in such a case IRS will release your information becuse they are goverment units. 

it doesnot matter what kind of status are you in. if you have lived in us for more that 6 month/183 days in year 2010, you are considered as a resident for tax filling purpose. so do not be afraid to get all the benefits and deduction that you get as a resident. if you need futher information about the deduction or you need any infromation about your filling status read first few pages of publication 17.

for quick residency check
http://www.irs.gov/publications/p519/ch01.html

for publication 17
www.irs.gov/pub/irs-pdf/p17.pdf

good luck

Me and wife works in the same company. My wife is gc holder and me as a F1 status. They pay me cash 12 dollars per hour through which I pay college fee. How to take all those benfits?

As per tax rules,  any income you have earned inside the usa or outside the usa , have to report. I have seen very few people report cash income but to benefit Earned Income Credit or some just do it.
Now it is your call.

gaywali , yo taa atti bhayo , cash ma kam gari 12 hrs kamaucha bhanera dhak laggauni hami justo gas station ma kam garnni haru lai.
Tero nam herdha tero body jatti thulo, dimag tetikai sano, vus bhaera ko dimag, accher padna nasakni, aru le padeko dekhera daha garnni, hola tailay MA degree paisies hola,Ki india bata degree kinera laies,  kam nepal ko madeshi bussiness house haru ko godowm ma justai kam garchas hola, tero ta nepal ma tannai cha haina, tero bau ko kam ki neta giri hola, ki airport ma,ki corrupt CIAA ma hola.
K ta american budhi patayera tesko khutta taaani tanni survive gari ra chas ho?

Sajjha ma ayera dhak lagauchas, 12$ cash kamauchas bhanera.
Hami justo gas station ma kam  gare ni afno mehenat le kamayeko 5 $ ma nai sukhi chau.

Bro: How about the side money? It was a big hit (Discussion) long time ago.

 Thanks to all for your valuable suggestions about tax filing. Now I am tension free.

If you read IRS instruction carefully, 6 months / 183 days rule does not apply to those in F1 / J1 visas. So, legal rule for students is to file non-resident tax return.

However, so far I found that IRS and Immigration does not talk with each other well. These are two different departments. I have seen people working legally getting green card without any issue. 

Regarding problem mistakely filed regular tax when you are students, lot of Nepali students do this. You will get more refund you file regular tax return 1040. Will IRS do anything? It depends if you are one of those unlucky one to be selected for audit.... if you are in audit, it might be a problem else should be fine.

Namaste Merajay,

I feel this is the right way to answer your comments. Well, its not my problem but my opportunity to earn 12 dollars. I dont know what is wrong with you, if I am able to earn 12 cash and you cant.Did you rot in gas station, thats why you are jealous. or     you cant study,  your shitty brain can't understand the pure language of knowledge or you are struggling. Its not my father, may be your father is a bhrastha  employee n have many houses in patan, kathmandu, bhaktapur amassed from ghus.

Anyway I feel humble to reply and want to send beautiful rose in valentines day to your GF. You dont need to PAY, I will,  as a courtesy.

Regards
Gaywali

kaliya,
if it gets audited then you might have to pay some penalties in addition to the amout you owe to the IRS. I dont think they will do anything else than that, its not an offense worty enough to put you in jail
and dont worry, you are dealing with IRS, not gabbar singh