Yes, I can use power button.
If there is in fastboot, after rebooting it goes back to fastboot.
If I remove battery and press only power button, it goes to CyanogenMod.
I cannot do anything else.
That means fastboot is working correctly. Did you install Nexus Root Toolkit as suggested in #2?
Inside Nexus Root Toolkit, choose correct phone model and then launch advanced utilities. Navigate to the quick tools and select fastboot-bootloader. Press List devices to ensure that your device is recognized by the PC. Go back and you can flash stock or other ROMs. If your device is not recognized by the PC, you could follow the instruction from the Nexus Root Toolkit to remove and re-install the driver.
Last but not least, I'm afraid you couldn't use adb command in bootloader since the system is not on.
As I mentioned before. In fastboot mode, my pc cannot see the phone. I use "adb devices" command it shows no device.
In CyanogenMod mode (just start screen loop), my pc can see the nexus s but I use "adb devices" command it shows "unauthorized".
I also use Nexus Root Toolkit for device list or somethings you said..
Any idea else ?
As your phone can't boot into system, adb won't work. Without the volume buttons, you can't get into custom recovery.
Your phone can only go to bootloader and therefore, fastboot is the only option. If your computer can't see the phone, try replace the USB cable or plug into another USB port. If that still won't work, probably driver on PC might not be loaded correctly. Mere re-installation of driver won't help. I have done it once in the past. You have to pick out all relevant drivers in USBdeview before re-install the driver where Nexus Root Toolkit provide a complete guide.
You may try to press reboot/ reboot bootloader/ reboot recovery under quick tools in advanced utilities of NRT.(remember to select fastboot - bootlaoder). If your phone responds to it, that means driver is loaded and PC can communicate with the phone. You need to make fastboot work before you can do anything to rescue your phone.