Why I didn't get my SSN or any other document after I came into USA?

It is a little unusual for an applicant for adjustment of status for the green card who applied for a work permit not to receive it after so long. I do note, however, that USCIS is delayed on many applications, including employment authorization documents. You may wish to check the current processing times and if over that, contact the USCIS Contact Center at 1-800-375-5283 to ask about your employment authorization. Once you obtain your work permit, you should be able to obtain your SSN shortly thereafter if you requested it also on the I-765 employment authorization application. If not or if the SSN does not come to you within 30-45 days after receiving your employment card, you should contact the SSA to ask about the card. Insofar as your question concerning the ability to obtain past Social Security or unemployment benefits, I do not believe that you would be eligible, but I do not practice in that field and suggest that you may wish to ask that question of a lawyer more familiar with that area of practice. Due to the limitations of the Lawyers.com Forums, Alan Lee & Arthur Lee, Esqs.’ (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.