L1B with I-140 and out of country

This is my situation.
I was in the USA with a LI-B visa and got out of the USA at the time of expiry and resigned with the employer. I have no H1-B visa.
During my tenure with my last employer, they started my green card process. They applied under EB-3 category and my I-140 was approved my priority date is in July 2014.
I learnt from my employer’s attorney back then that it’s not their practice to withdraw approved Forms I-140.
Currently am in Canada. I just learned that priority date is now current. I do not intend to go back to the employer that filed my GC.
What are the options available for me to take forward my GC process further?
Any information/help is appreciated.