Converting eDrawings (.easm) files back to original Solidworks parts (.prt) will be possible only if the original creator and the one that exported to eDrawings in the first place did select that option in export settings. Otherwise, there is really no way how to convert .easm files as they are indented primarily for viewing and publishing purposes.
Convert SolidWorks eDrawing assembly data to CAD 3D part or component.
We found one software available in the database for this conversion.
Microsoft Windows software - convert easm to prt on Windows
A 2D and 3D CAD construction software
Convert from easm file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.