beaglebone booting

I was following a guide from a following link to create a partition on SD card. I was using beaglebone Black's SD card slot to do the partition as beaglebone has Linux and contains all the packages to create partition.

When I gave a command to read the partition and error popped up that
"Re-reading of partition failed due to error 22. The kernel still uses the old partition table. It will be informed after next rebbot or running partprobe or kpartx."
So I ran partprobe and kpartx but I didn't work. So I reeboted the system. And it stopped booting.

Can anybody help on the problem ?