Possibly Broken Log Shipping
Transaction log shipping is an easy (and usually bulletproof) way of preparing a disaster recovery server ahead of time. The subscriber continuously restores transaction log backups from the production server.
To find this problem, we look for databases in a restoring state that haven’t had a log backup applied in the last 2 days, possibly indicating that it’s a broken log shipping setup.
Find out if this database is supposed to be part of a log shipping setup, and if so, check the SQL Server Agent jobs that should be copying and restoring the backups.