Hi nikileshsa,
This is the problem with relying on only an embedded bootloader, if it breaks you have lost your window into the device and are stuck without a BDM adapter.
One way to test for this is to monitor the reset pin with an oscilliscope.
If blank or jumping off into uninitialised memory because the bootloader thinks there is code there you will see the reset pin hiccupping in response to the COP or other resets occurring.
If it is supposed to be in bootloader mode and you see activity on the reset pin then the device is blank or the bootloader corrupted!
You need a BDM adapter to re-install the bootloader.