UPDATE(2019-10-11): I got back my STEEM. Thanks to @oflyhigh and all people who helped.
OpenLedger disabled STEEM/SBD withdrawal without even an announcement on steemit.com. It seems they've emptied their wallet.
OpenLedger announced on 6th August on their website that Steem will be delisted and the deadline for customers to withdraw was 19th August. I didn't find a post on Steemit.com .