Recover deleted in cell in assignment

Hello, In my last assignment C5_W4_A1_Transformer_Subclass_v1.ipynb, i accidentally deleted a cell by pressing the key x on the keyboard while it was selected. Now i am unable to proceed further. I am getting the following error in the grader “UNQ_C6 wasn’t found in code” .Where can i find the contents of this cell. I tried to restart the kernel but no luck . What are my next steps to either retrieve a clean copy of the assignment of just the content of a particular section ?

Rename your notebook, then get a fresh copy of the blank notebook (by using the Help menu).
Then you can manually copy your code segments from your saved copy into the fresh blank notebook.

In addition to Tom’s instructions for getting a clean copy (which are useful in lots of scenarios besides this one), it might also be worth pointing out that the notebook supports an “Undo” function for the next time something unexpected like that happens. There’s general “Undo” which is Command-Z on MacOS + Chrome and also under the “Edit” menu, there is “Undo delete cells”.