Can I file I485 by myself if my old employer do not file using old employer I 140?

My priority date is sep 2015 in eb3 with Employer A.

Recently I changed my job to employer B and perm and I 140 are still in progress.

Can I apply for I485 by myself if my priority date becomes current with old employer perm and I 140 ??

No, your employer will need to submit I-485J that states that the I-140 job is still available for you and that the sponsoring employer has ability to pay the wages.

Thanks for the reply … which employer?? Old employer or new employer??

Your old employer if you are trying to use their I-140.