Loading Bootloader into P89V51RD2
You can restore it using a parallel programmer. Here are the steps:


Download boot-loader from FlashMagic website. &amp; extract it.
Load the corresponding HEX file to your programmer software. Be sure that HEX file is loaded at correct address i.e. 0x10000 else correct it manually. 
Overwrite address from 0x10000 to 0x10002 with 43 B1 02 respectively.
Burn the customized HEX file to MCU with your programmer.
Enjoy Programming! :-)


You can also take a look at this.