If you had L-1 visa, then you came from a country which needs visa to enter the US. As canadian Permanent resident you still need US visa to go there. depending how long you have been out of status, you banned yourself to receive a new US visa. (3 years penalty if you overstay more than 6 months but less than a year, and 10 years penalty if you overstay more than a year). you could check that in a link or information below.
Probably the best way to re-enter the US, is waiting three years and applying for a Canadian citizenship. With Canadian passport you won't need any visa to go there.
http://www.travel.state.gov/visa/frvi/ineligibilities/ineligibilities_1364.html
Classes of Aliens Ineligible to Receive Visas
(B) ALIENS UNLAWFULLY PRESENT.-
(i) In general.-Any alien (other than an alien lawfully admitted for permanent residence) who-
(I) was unlawfully present in the United States for a period of more than 180 days but less than 1 year, voluntarily departed the United States (whether or not pursuant to section 244(e)) prior to the commencement of proceedings under section 235(b)(1) or section 240, and again seeks admission within 3 years of the date of such alien's departure or removal, or
(II) has been unlawfully present in the United States for one year or more, and who again seeks admission within 10 years of the date of such alien's departure or removal from the United States,is inadmissible.
(ii) Construction of unlawful presence.-For purposes of this paragraph, an alien is deemed to be unlawfully present in the United States if the alien is present in the United States after the expiration of the period of stay authorized by the Attorney General or is present in the United States without being admitted or paroled.
(iii) Exceptions.-
(I) Minors.-No period of time in which an alien is under 18 years of age shall be taken into account in determining the period of unlawful presence in the United States under clause (I).
(II) Asylees.-No period of time in which an alien has a bona fide application for asylum pending under section 208 shall be taken into account in determining the period of unlawful presence in the United States under clause (i) unless the alien during such period was employed without authorization in the United States.
(III) Family unity.-No period of time in which the alien is a beneficiary of family unity protection pursuant to section 301 of the Immigration Act of 1990 shall be taken into account in determining the period of unlawful presence in the United States under clause (I).
(IV) Battered women and children.-Clause (i) shall not apply to an alien who would be described in paragraph (6)(A)(ii) if "violation of the terms of the alien's nonimmigrant visa" were substituted for "unlawful entry into the United States" in subclause (III) of that paragraph.
(iv) Tolling for good cause.-In the case of an alien who-
(I) has been lawfully admitted or paroled into the United States,
(II) has filed a nonfrivolous application for a change or extension of status before the date of expiration of the period of stay authorized by the Attorney General, and
(III) has not been employed without authorization in the United States before or during the pendency of such application,the calculation of the period of time specified in clause (i)(I) shall be tolled during the pendency of such application, but not to exceed 120 days.
(v) Waiver.-The Attorney General has sole discretion to waive clause (i) in the case of an immigrant who is the spouse or son or daughter of a United States citizen or of an alien lawfully admitted for permanent residence, if it is established to the satisfaction of the Attorney General that the refusal of admission to such immigrant alien would result in extreme hardship to the citizen or lawfully resident spouse or parent of such alien. No court shall have jurisdiction to review a decision or action by the Attorney General regarding a waiver under this clause
