Generally, it’s a problem if you entered the US without a visa (or without ESTA). If you last entered the US more than six months ago without a visa, then you are probably not eligible to get a green card from within the US. You’ll have to get an I-601A and get your green card at a US embassy. If you entered the US at some point, and then later entered the US with a visa, you may have a fraud problem. That is, in order to get a visa to the US, the US generally asks if you’ve ever been in the US and how you entered. If you told the US that you entered without a visa that will make it unlikely that you’ll be granted a visa. If you were asked about prior entries to the US and you did not disclose the entry without a visa, you’ll have a fraud problem that will require an I-601 waiver (not I-601A waiver).
If you need to talk to an experienced immigration attorney. We’ve helped hundreds of people traverse the complicated immigration and citizenship process. We would love to help you as well. Call (617-766-0214) or email firstname.lastname@example.org to get in touch.