Convert EPRT to PRT

eDrawings that were exported using Solidworks software (such as .eprt files) are saved in a proprietary format used for publishing and viewing only, not for further editing or conversion, which makes eprt to prt conversion (or recovery of original) very difficult.

You cannot really convert .eprt files to any other format,  the only way would be to contact the author or whoever send you the .eprt file in first place and ask for the source file.

Simply put, it is impossible to convert EPRT to PRT directly.
Thus, there is no so-called eprt to prt converter or a free online .eprt to .prt converter to be found.