There are to possible cures
First is that while working with the rifle, pulling the bolt open the operating handle GOT PUSHED in, take hold of the bolt handle pull back and then outwards, it should move just a little to release the bolt.
The second is that it has an empty chamber bolt hold open, for this there will be an extra peice thru the trigger gaurd plate, that has to be moved when the bolt is pulled back.
hope this helps