Laptop won't connect

[#1]

Wifeys laptop won't connect to wi-fi, all other devices working well. HELP, she's going nuts

[#2]

Try temporarily turning off router's wifi security and see if it then connects; if so, turn security back on.
Delete the connection in wife's laptop, and reinput the router's security credentials & try to reconnect.

[#3]

Could it be the laptop has an old dhcp allocation and something else is now connected on that address?

Mark

[#4]

is it macbook?