Received an error like this and accidentially deleted a cell

[Mujassim_Jamal]

Yes, Check this out:

How to Get a Clean Copy of an Assignment Notebook

If you want to restore the original unmodified state of any of the notebooks or the other files associated with any of the assignments, you can use the “Lab Help” menu of Coursera Labs to do that. The first thing to do is to rename the existing notebook, because this procedure will not overwrite existing files. You need to move the current version of the notebook aside or delete it. The advantage of renaming is that you can later copy any completed work as desired to the fresh copy of the noteb…