If you can try and save your work.
Ask someone nearby if they are having the same problem - it might be a wider network fault.
Use Ctrl+Alt+Del to see if the application is responding.
If it's not, try closing the application and re-opening it. If re-opening it seems to work, then you could try to recover a previous state of the document by following instructions found here.
If it's still not responding contact a member of Library staff or NUIT.