PLEASE HELP MY MAC PRO WONT BOOT INTO OSX

I Have a Mac Pro 1,1 running el capitan. i wanted to put windows 10 on it so I tryed putting a hard drive from a windows 10 laptop and it worked The problem was that I can't get back in to OS X. I pulled out the drive so that it would boot if the OS X drive and it sayed no bootable drive detected -- insert boot drive an press any key.i tryed resetting the pram, booting off an OS X cd, recovery mode, holding option, and nothing works. I have a lot of important stuff on this computer and I need it for school. could the windows drive have changed the boot efi? It did say 64 bit.

please help!