Need help

My HDD (for PS2) was working fine. I pulled it out and connect to my PC to copy some games. When I put it in my Ps2 again, HD Loader and others loader don't seem to regconize it

PS2 uses a special file system I believe, putting it on your PC altered the file system, rendering it unreadable.

So could you help me out? I'm really don't know what to do. Before I connect it to my PC, when I boot my PS2 there is yellow light coming out but now it isn't.

I would expect it needs reformatting to the correct file system.

I connect it to my PC again and now my Winhip can't recognize it. Ah, I hate this

well..better leave that to the expert....
go to your gameshop and ask it..... ;D