If diskpart does not see the drives, then it possible that the drivers are not loaded correctly. Remember to use the 32-bit drivers, as the SRD is 32-bit based. Either try other drivers, or create a custom recovery disk:
Open BESR, click on the TOOLS icon. From the menu along the top, click TASKS, then CREATE RECOVERY DISK... and follow the wizard. This wizard compares drivers on your computer against the drivers on the recovery disk, and creates a recovery disk with those missing drivers.