I have 2 tax questions..?

Always browse this sub and hoping i can get some help here on 2 situations i have that have arose:
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I have never filed taxes. Not that i know of. I pay income tax, i had a cash only business, this year i have a normal 8-5 job again, wondering what i need to do to get taxes done correctly.
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Gal friend has filed taxes every year, and the last 2 someone has taken her return and or financial information. This year she filed and said she would be getting 800+ish back. She was informed yesterday that she owes 4,000 or something like that. Possible to see where her return went to, or how to dispute it?