I have 2 Nexus devices and I'm trying to update them via USB . It's worked fine before but now they don't seem to connect to Windows 10 at all , not showing up in device manager .Have USB debugging checked also tried MTP and PTP settings have tried different cables but get nothing when I connect to USB on the computer , Used to get a window on the tablet asking me if I wanted to connect to computer but now nothing . I've been googling this for ever but can't seem to solve it , please any advice ?

Have you tried with a different cable?

It sounds like a problem I had,I found that you need now to go into the nexus settings and select Storage and USB if I remember will allow you to access Computer if connected.sorry it's a bit vague but I only did it the once,and as I'm away from home I cannot try to re trace my steps to give you a better description of what to do,but I'm pretty sure that when you connect Nexus to Computer and select storage usb it shows up in that section and asks if you wish to connect

You can also just drop the notification bar down when the Nexus is connected, and select USB connection options from there.

You can try installing wugfresh development tool ( no idea if it works properly in w10)
Or you can install airdroid on the tablet to upload/download by WiFi.

Thanks for the help , turns out it was the cable , I tried 2 cables which didn't work then came across a third cable which I hadn't tried . It then connected immediately . Thanks again