What do you do when your monitor is not detected by windows?

First clear your mind and clam down think about your problem and break it down step by step 1. Power on: Check and make sure your monitor power is turned on; usually a green light indicates that the monitor has power. 2. Plug in: Check if the power cord is plug in. 3.The notice: is there a notice on your monitor screen saying that no connection has been found or something similar to that? If so then check the cable connecting your monitor to the computer, make sure to check both ends sometimes this cable can become lose even if you never go back there always check your cable. Even if it's not loose unscrew it and screw it back on. 4. Swap Monitor: if you have access to another monitor swap it and see if the other one is giving you the same trouble. 5.Did you hear Beeps: A defective graphics card should give you error beeps, usually one long beep then 3 short beeps (this can be different depending on board or biOS) you may need a new graphic card or your onboard graphics may have gone bad.(replace card or add card if on board has gone bad, although some people replace their whole motherboard in fear of other components may be going bad as well) 6. BiOS maybe: you may need to check the biOS if you have onboard graphics and are using a graphic card instead of the onboard graphics your computer may have for whatever reason switch back to using the onboard graphic port you may have to access your BiOS and change it back. 7. NOTE: WARNING! Never take your monitor apart very dangerous! Dispose of it properly and buy a new one if it turns out that the monitor its self is bad