Okore has been ruled out for the remainder of the season after suffering the injury against Newcastle United last month, but Vlaar has insisted that the Denmark international can make a successful return.
The 28-year-old told the club's official website: "Jores is so unlucky with his injury. He's going to come back very strong. A lot of it is mentally, and that's where we have to help him, because sometimes it will be difficult.
"I think he did really great in the games that he played. I know what he's going through and I hope that if we can have good results, it will help him feel better.
"We try to help him as much as we can. He has to go on. It's going to be a long way but he's going to come back stronger."
Okore has made four appearances for Villa after signing from Nordsjaelland during the summer.