Head of Household filling

I would like to file my 2019 tax return as a Head of Household. I do qualify for the filing as stated by IRS (single, both parents lived with me in my house whole year, they make less than $4,200 a year and receive only Social Security, I provide more than half of my parents total support each year).

However, their CPA did their taxes and already filled their tax returns for 2019 and failed to check Someone can claim them as dependent.

Can I still file my tax returns as a Head of Household? Would IRS accept my tax return? Anything can be done to make this happen? Any help is appreciated. Thank you!