I'm missing a hard drive

A few days ago my computer turned off, and I got a
message, press any key to reboot. I hit a key and nothing
happened and the same message came up. So I gave my
computer a cold boot, it loaded back up, and I got a new
message, it sead some thing like start up failed back up
data and replace hard disk. So I replaced my master
drive. I installed XP on the new master and all is well
with that hard drive. However I back up all my data on my
slave drive. I can't open the slave drive now. It appears
in my computer and disk manager, but if I click on it it
asks me to format. How can I open and retrive my data
before formating my slave drive?