Laptop no longer talking to projector windows 7

Following a Windows 7 update my laptop would no longer recognize my projector, which it had been doing for some years and immediately prior to the update. I also find that my laptop now no longer recognizes my monitor, which again it had been doing for some years. Different cables are used so it is not a cable problem. I have been through all the obvious things and have looked for updates to the graphic driver, but no better updates available.
When I plug either of these items in to my laptop the screen resolution on my laptop changes as if it is recognizing the additional hardware, but in neither case is anything displayed on the remote device.
Can anyone give me some ideas about where to go next with this?
Thanks in anticipation of someone's help.
Tim