[Wireless Network connection error: incorrect key?]

after an internet session yesterday a problem has occured regarding the security key for my wireless network, when trying to use it today, no luck.
it was set up for auto connection.
it now will not connect and shows the error as incorrect network key.
i have not changed this and my other computer still connects without error.
how can i correct the network key.
i am almost bald and this problem will probably complete the process.

 

Have you gotten into the router and verified the key.
Plenty of people out there make it a hobby to hack into routers and change keys and passwords.