Did she file a return for you OR did she claim you as a dependent on her return? If she filed your return then you need to get a copy from her or from HR Block. You have to ask your employer for another copy of your W2.
Request a transcript from the IRS
https://www.irs.gov/individuals/get-transcript
Or get a copy of your return using form 4506
https://www.irs.gov/pub/irs-pdf/f4506.pdf
