The playerped.rpf file is located in the following directory within your main GTA IV installation: Grand Theft Auto IV\pc\models\cdimages\playerped.rpf Essential Modding Best Practices

Restart the game. Niko should be back to his default, tracksuit-wearing self. Avoiding Future Crashes

“Meaning?” Niko asked.

(Optional but Recommended) Rename your current playerped.rpf to playerped.rpf.old . Copy and paste this backup file into the directory. Launch the game and enjoy your restored Niko!

If you installed a mod and your game crashes, you need to restore the default file. This is the "Universal Backup" method.