I have changed only cmos battery then I turn on computer it's start properly but no monitor. I wonder what's wrong with this problem could anyone solve this? I appreciate for any comment from all of you.
There could actually be several possibilities. The common "no display" suspects are PSU, GPU, RAM, or mobo. Sometimes this problem is just a disconnected 4/8 pin ATX plug.
In any case, check out the sticky (click on link in my signature). This troubleshooting guide was designed to help with boot problems. Make sure you perform every step, regardless of how irelevant the step may seem.
1) Does you motherboard have onboard video?
2) Are you using an add-on graphics card?
Because this sounds exactly like what happens when you're using a video card but haven't disabled the motherboard's built-in video adapter. When you change the CMOS battery, the BIOS will probably reset to factory defaults, so your motherboard will "forget" that the onboard video was turned off. If that's the case, plug the monitor back into the onboard plug, go into the BIOS and disable onboard, then turn off the machine and plug the monitor into the video card. It should work now.
If not, then you likely have a more complicated problem. In either case, it would help to know the specs of your motherboard and video card (if any).