If the visa was H1B, H4, L1 or L2 she could return with that. But the B1/B2 visa will be useless because of the pending I-485. I hope she didn't overstay the visa before leaving the US; if she overstayed by 180 days (or longer) that could make her unable to reenter the US even if she found back the Advance Parole.
She'll need to go to the US consulate with her passport and I-485 receipt (preferably the ORIGINAL receipt) and ask about getting a Transportation Letter (or whatever other document they would issue for this situation) to allow her to return to the US. She will also need to bring a police report to the consulate.
Having a copy of the Advance Parole would make things smoother ... that card is a combined EAD/AP so she might have shown it to her employer who took a copy of it. Then if they fax or email it to her she can bring that copy to the consulate.
If she can't get a copy of it, she should at least be able to tell the consulate the approximate issue date. It would make it easier for them to check the records to verify that it was issued before she left the US.
Update:
No Jack she did not overstay the visa before leaving the US.
1. She went to the US embassy in London, and she was told they cannot issue any document of any sort to enable her travel, because she was not a US citizen or Permanent Resident. She was given the phone numbers to the US consulates (?) at Shannon airport and Dublin airport, Ireland, and asked to call them. That they are the only ones who can issue a travel document.
2. We called Shannon Airport in Ireland, and they were surprised we were directed there by the US embassy in London. They said there was nothing they could do.
3. In meantime, the petitioner tried and was lucky to get an Infopass appointment with the local USCIS yesterday. At the appointment, the first question by the USCIS lady was,
"did you make a copy of the Advance Parole/EAD card?" She did not have a copy. (Lesson to all, always have a copy of whatever cards you get).
4. The USCIS lady was very nice and helpful. She checked on their system, and said that though the Adjustment of Status interview is next week, the I-130 is already approved. Had been approved back in October - meanwhile, a check online still shows the I-130 status as "Initial Review". Go Figure.
5. The USCIS lady advised that since the I-130 is already approved, and because she still had a valid US visa, she should get on a plane and come into the US. She said she must hold copies of all correspondence from the USCIS, especially the interview notice, and Advance Parole approval notice.
6. With baited breath, my relative got on a plane in London this morning and arrived in Dallas 4 hrs ago.
7. She presented her passport, and all the copies of documents that she had
(Adjustment of Status Interview notice, AP approval notice, Police Report from London etc) and told the IO that she lost her AP card in London. He then took her to secondary inspection and told her to wait. After a wait of about one hour, she was called. She was asked when she left the country, and why she left the country. She was then asked to fill out an I-94, and paroled in. According to her, the IO said
"You need to fill out an I-94 so I can parole you in."
She is home now.
Thank you for your help.