Which is combination of keys to open console. I need repair a broken gnome Centos. There should be something like alt+f1 in Fedora?
It depends on exactly how and why it's broken, as well as which stage of the boot process you try it in.
Various things to try:
If the brokenness isn't because Xorg is hanging or crashing, you can use the VT Switch keys to switch to a virtual console. This won't work if you have broken graphics drivers, but you may be able to override it and get back to a console anyway if you use the next option. Alt+F2 is a common way to switch out of VT-1 to a console (the reason Alt+F1 doesn't work is likely that your X server may be running already on VT-1). You may also have to add Ctrl to the key combinations if you're in Xorg.
If your kernel has support for it compiled-in, you can use Magic SysRq key combination: Alt+SysRq+r (for a standard US QWERTY keyboard; see the wikipedia article for others.) Once you do this, try the VT switch key combo.
Try booting into "recovery" or "single" mode: when booting, interrupt GRUB by pressing a key, then edit the kernel command line: remove
quiet(if they exist) and add
recovery. This should boot up without Kernel Mode Setting and without trying to start Xorg; you should then be able to login to the command line.
Try putting the hard drive into another system (or boot another OS on the same system) and perform appropriate fixes in the config file(s) to get it back to a bootable state.