Blinking Dash And Message C0000218

i have a older hp pavillion windows xp comp.something started updating on my com.then we shut it down.afterwards tried putting it back on i saw the first blue hp invent screen and then after wards it goes to this black sceer with a blinking dash on the top right corner.i tried hp recovery at start up and a message STOP:COOOO218 {REGISTRY FILE FAILURE}
THE REGISTRY CANNOT LOAD THE HIVE (FILE):
\SYSTEMROOT\SYSTEM32\CONFIG\SECURITY
OR ITS LOG OR ALTERNATE.
IT S CORRUPT,ABSENT,OR NOT WRITABLE.
I do not have a recovery disc.tried my friends parts on my computer and still nothing.he has the same comp.hard drive , memory ,slave cables .the mother is good i think .when i took out the memory it started beeping.any help please.cant afford to buy another.