well.. it's difficult to answer to such a question..
first of all: do you have any backup?
then.. how many HD?
which error message do you see?
finally: 8.1 is in EOL state and unsupported.. if you have a backup, tihs is the time to move to latest stable 9.2
if you don't have a backup but your hd(s) are ok, you can move to 9.2 too..