external HD switch problem from internal to external

man i never had a problem since using these flash & updates but now?

>

my HD drive doesn’t show up so i went into the maintenance section and noticed it shows itunes internal HD?

>
when i try to change it my HD shows up and after i click yes a CAUTION fag says if i select the external HD it will wipe my HD clean?

>
i don’t want that is there another way?

>

tks for your help 

oops i found a thread on this

 

but can i put a dummy usb drive into the slot and then flip it over to external drive then plug back in my HD?