When you say that you can't access the SD card, was everything ok before using ROM manager?
As for a ROM, I can only suggest a DHD ROM... I know that this should work on your phone, as Scotty85, one of our guides, has an Inspire and has confirmed that the DHD ROM's work on it.
Do you want a Sense ROM (similar to what was on the phone before) or a vanilla Android ROM (like what is on the Nexus range of phones)?