Company Revoked Offer Letter i have resigned from previous company

Dear Sir/Mam, greetings of the day! Few days before I found an opportunity to get placed with a private organisation. who take govt. projects and provide them the staff on outsource basis, I was selected and got offer letter, and joined the govt. sector on outsource basis, and also resigned from my previous job, but after two days of joining, company personal told me that govt. official will take your interview and you have to perform ( they told me this verbally, and nothing like that mentioned in my offer letter as well as in MOU by the company). So, if govt. official will reject me, what are my rights, to sue the company, because I am the only earning person in my family, I was placed and to find better opportunity I have resigned from my previous job, and now the new company saying this. please help!