We bought the property in June 2019.There was a lien attached to this property since 2014{ a demolition bill of $12,770... by County}. The County has mistakenly assigned that bill to the wrong address. This issue had not been corrected until sometimes in 2017.The lady at the Office of Tax Commissioner said that we are supposed to pay that bill {$12,770 by December 20th 2019}, even though that issue occurred well before we purchased that property. She suggested that we talk to our closing Attorney whom we closed the lot and the Title Insurance. We had contact with the Closing Attorney since October 23th 2019. On November 4th, they answered that the Attorney was on vacation and the Secretary was looking into this.Four weeks later, nothing happens. The Title Insurance is not answering yet. So I need some advice as soon as possible.

I would call around at the county office until you can find the person who can fix this. They made the error they should fix it. Once you find the right person it should be easy to get fixed. I wouldn't get an attorney involved until I had exhausted all avenues with the county. Get all your paperwork together to prove the error so that they can easily review the problem without having to do research to get back to you. An Attorney can do this for you but they will be charging a hefty hourly fee for something you should be able to do yourself.

Did you buy a lot or a house?   Lien should have shown up in title search.   Did your title attorney discuss it with you?  Did you get title insurance when you purchased?  Was there demolition?  Some liens do survive closing depending on who you bought the lot from, how you closed, where you closed, etc.

@Tuyet Changivy   I'm not an attorney so I can't give you legal advice.  But I have dealt with code enforcement liens in Atlanta and can share my experience.

1) This isn't as urgent as you are making it out to be.  It's theoretically possible that the county could try to levy on the property to collect the lien, but it's not normal practice.  Even if the county did levy, it's not a quick process.  These liens usually only get paid when property changes hands.

2) The County Tax Commissioner can't help you here.  They didn't create the lien.  Their answer will always be "pay up."

3) Yes, your closing attorney should have found this lien in the title search (assuming it is recorded).  Still, you may not have any recourse.  Title insurance policies often have exclusions for municipal liens like this.  It's worth continuing to call the attorney, but don't assume they will solve this for you.

4) As @John Underwood suggested, your best bet is likely to get in touch with the office that issued the lien.  In the City of Atlanta it would usually be the Atlanta Police Department.  In other jurisdictions it could be part of the building department.  If they did lien on the wrong property (it happens), they will likely release the lien for you.  Start with phone calls - you may not get responses to emails.

5) Another possibility is that they put a lien on your property for "clean and close," which is when they board up a vacant property and clean up trash and overgrowth.  Sometimes this shows up as a "demolition lien" even if the property wasn't actually demolished.  If this is what happened, you're on the hook for it now.

Unless this has changed, they can only collect those liens for 7 years. Wait another year and it will fall off. I've bought many lots with the original demo lien being cancelled, because it's been 7 years. Just like tax liens. They treat them like judgments in Georgia. At least they used to years ago. Haven't dealt with lots in a while.