Cannot connect to Home Network - BT router

I have a lenovo G505 laptop - it will no longer connect to my BT home hub despite it showing as being available. I suspect it might be to do with the fact that it is has a passkey - I entered it yesterday when prompted and it connected fine, but now I'm not being given the option of entering the key.
I've also tried connected using the BT wifi (as opposed to homehub) but once again it will not connect me.
I've been through all the troubleshooting options, and searched under every term I can think of, but nothing is working.
Any suggestions?

Have you ran the troubleshooter, this will reset the wifi adapter which will generally reestablish the wifi connection. Otherwise a hard reboot of the router should work. Just unplug the router from power outlet for 2 minutes and then plug it back in.

Thank you. I did reboot the router as suggested but no change. In the end I decided to reset the laptop back to factory settings and went through all the set-up system again, and this time it seems to have worked without any hitch. I think the problem, looking back on it, was that during the first set-up I was prompted for a Microsoft UN & PW which, though I entered it correctly, I don't think it was later recognising. This time around I created a brand new one, and so far there've been no further problems.