She said in a statement, "I am confident that our backup data is secure and we have the resources to fix the situation ourselves".
"It will take time, but with patience and hard work, all of our systems will be back up and running as soon as possible", Diorio added.
Earlier, Diorio said there was no indication any data had been lost or personal information compromised.
The hackers demanded a ransom of $23,000, but on Wednesday Diorio refused to pay, saying the county's backup systems could restore much of what had been disabled.
Third-party experts retained by the county believe the ransomware is "a new strain" known as "LockCrypt", and "very little is known about it", the county manager said.
It will take days to restore Mecklenburg County's computer system, local officials said, leaving residents in North Carolina's most populous metro area facing delays or disruptions to county services.
All county-wide ITS systems will be shut down until further notice, the county announced. "And there was no guarantee that paying the criminals was a sure fix", Diorio said in a statement.
Population numbers for Mecklenburg County jails are expected to rise, the county said on its website, because the inmate releases have to be handled manually and the entire process is significantly slowed down.
A North Carolina county was working Thursday on the lengthy process of fixing its computer systems after refusing to pay off a hacker who used ransomware to freeze dozens of local government servers.
"If you pay the bitcoin, there is always a risk they won't give you the encryption key", she told reporters. "We really don't want people to just show up and then get mad when we can't help them", Diehl said.
The attack happened when a county employee opened an email attachment that infected the county's computer system with spyware and a worm.
Meanwhile, payments to the tax office must be made with a check, cash or money order, and code inspectors have been slowed down by having to use paper records, according to a list of affected services.
County Manager Dena Diorio said Tuesday she is debating whether to pay the ransom.
At this point, officials don't believe any information has been stolen, but malware was discovered on about 30 servers.
Stay tuned to WFAE for updates on this developing story.