Sounds like a crank out casement that has a sash that won’t move. Usually this comes down to one of three issues:

1. The sash has even painted shut and the paint needs to be cut open to work properly (this is usually pretty easy to spot and doesn’t sound like your issue)
2. the operating hardware is either binding or is malfunctioning and a repair + replacement will need to be made
3. the “keepers” or locks on the sash itself are not moving from their locked position when the lock/unlock latch is used, causing the sash to stay in the same place

Some pictures will definitely help!