If you accidentally delete part of your document, you may be able to recover it by using the revision history feature. This feature causes your document to revert to a version that was previously saved in the document editor. 

To use the feature, go to your document and click on the three vertical dots in the upper right-hand corner of the screen. Choose "Revision History." You will see a list of previously saved versions of your document. Click on the version you want to use and choose "Apply revision."