HELP with OS X LEOPARD START UP WITH SMILE FACE AND ? blinking

Blue screen with two buttons

one with circle arrow (refresh) and an arrow button

but it doesnt say what its for, its just blank and all blue screen except that 2 black n white buttons

do i click arrow ------->? i did click the arrow but nothing happening so i click the circl arrow and a wristband watch appeared and it stopped, nothing happened either.

sorry for my bad english, not my first language

i clicked solve to a question because i learned something new with press alt while start up (thanks). but not working after i click arrow

it doesnt show up! just blank blue with two buttons

i have the os system on external hard drive is there any way i can re-erase and reinstall os and see if it will work?

do i plug it in usb and let start up, whats the trick?

it happened after i triedto time machine on my external hard drive then halfway it froze so i had to restart it that how i am having this problem

Can i replace old hard drive with one of my external 1tb hard drive as main and remove the old one to run the g5 with external hd?

i opened g5

i found hard drive loose and the plug looks like unplugged

what do i do??

i looked up on youtube

http://www.youtube.com/watch?v=EmeKobbV6Zg&feature=related

is what i see

I guess i need to buy new internal hard drive at best buy

is this right one

http://www.bestbuy.com/site/Western+Digital+-+Caviar+GP+500GB+Internal+Hard+Driv e/8682311.p?skuId=8682311&id=1197679235869

?

may we talk on ichat?

anonymous5apple@yahoo.com

im on Aim

Anonymous5Apple