I can't speak for your lawyer. Your bankruptcy petition must disclose the amount of money you earned, by source, for each of the past two years. I get that information from the W-2's and 1099's that my clients give me. In addition, I turn over last year's return to the trustee. But there are other ways to get the same numbers, and a transcript of return will suffice in lieu of last year's return. So tell your lawyer about your problems finding documents and let him suggest alternate ways of complying.
Your lawyer is working for you. If you cannot locate something, he will work with you to get it another way. As Mr. Oney stated, you can order a transcript of your return from the IRS which should be enough to get the information needed.
It is not your lawyer who needs this but the Trustee. Your lawyer should be telling you where you can get copies. You can get copies of your tax transcripts free of charge from the IRS by calling 1 800 829-1040. You do not have to pay for copies of the returns, the free transcripts are good enough. If you are that afraid of your lawyer and his reaction, get a lawyer you feel more at ease to work with. A lawyer is on your side, not someone to fear!
This answer cannot be a substitute for legal advice which requires more information from the client than can be obtained in this forum.