if you edit the view on the library can you add the column back in (it will display the name of the workflow)?
I tried to modify the view but its not listed?? It was before??
Ok just check your workflow settings - there is a setting checkbox that says about creating a column for the workflow.
The workflow status column always has the very same name of the workflow. Is the checkbox that Cassy Freeman mentioned active in workflow settings?
If you don't have any option to bring back the column you could publish the workflow with a new name, which basically creates a new version 1.0 workflow with that new name. It therefore should also create a new workflow status column. If you do this you should delete the old workflow to not have duplicate workflows in your system.
Using this approach will surely bring you a new status column but you will loose all workflow versioning of your old workflow.