How do I fix my monitor problem: D-SUB OUT OF RANGE 99.0 kHz/121 Hz?

99.0 kHz and 121 Hz corresponds to 1024 by 768, well within the range of most monitors, so the problem must be the 121 Hz refresh rate. Power up the computer and immediately press Shift and tap F8 to invoke recovery mode.  Select "repair options", Troubleshoot, Advanced, Startup Settings, and Restart.  You should be presented the Advanced Boot Options menu.  Select Safe Mode.  Log on and select the 60 Hz refresh rate in Display Properties.

the refresh rate sent by the graphics is not a refresh rate the monitor can use , look in the monitor handbook for usable refresh rate , usually 60 or 70 will work with any monitor, very few monitors can accept such a high rate

There is a way to access safe mode in Windows 8 before Windows starts, it's not good practice and can cause file corruption but sometimes it's the only way. Basically what you need to do is to switch it off when Windows is starting up, then restart it and do the same again. As a result Windows will decide that it's not able to boot, so next time it'll bring up the advanced boot options before loading the whole operating system, and it'll do this in VGA mode. That'll allow you to see what's happening, you won't need to choose safe mode, just choose start in VGA mode, then once it's going you can set the graphics mode correctly. You can also get to this point if you have a Windows installation DVD and boot from that, but most people just have computers with Windows pre-installed and no DVD. Once you've got it going make sure that either the monitor driver is for a plug and play monitor, or if you can find drivers for it on its manufacturer's website then install those. If it's set as non-plug and play then Windows won't know which display modes it can handle so can allow you to choose an unsupported mode, this is probably what's happened. If you've had to use the switching it off method rather than an installer DVD then you should scan the hard drive for errors afterwards.