It might be hard to get through because the IRS has reduced staff, but you can request to be on a payment plan.

Also, if you are unsure what your income is, you can request a wage and income transcript. Employers are required to file w2 and financial institutions and people who hire you as an independent contractor are required to report the income paid to you to the IRS (this is their way of knowing how much you should owe). This transcript will help you identify sources of income and report any withholding on your half you may have had (so you dont leave off payments). This is what they're getting $10k from. However, if you earned income that's not included on the wage and income transcript, you are still required to report that. Do not leave it off the return and hope to not be caught.

If you're able to, a CPA can help you navigate this to make sure your return is being prepared correctly. Depending on what year you're filing, there are deductions you can utilize

You should file the late returns and pay what you can if you cannot pay the full balance. The IRS will send you a letter if they assess a different tax, you're short on the payments, or if they assess failure to file penalties and interest. Sometimes, you can get a one time waiver of penalties, a cpa should be able to help with that. If you had an extenuating circumstance like health issues, out of the country, etc for not being able to file, a "request for penalty abatement" is an available remedy.

Engage a cpa if you can, file the returns, and pay as much of the balance you can. Continue to pay the balance and potentially look into a payment plan. You can accelerate payment and pay it off sooner, because interest will continue to accrue, but it protects your credit and avoids asset seizure and wage garnishment.