Why router dont allow me to connect to WLAN network?

[lucky.BOY]

Hi,
I have bought a new laptop yesterday, but I failed to connect it to internet via my D-LINK DSL G664T wireless router. I have 3 computer connected and working this way, but i cant find out the way to connect my notebook...
I have enabled IP adress from DHCP, i can see the network, i know the password but i cant connect. Can somebody please help me and list here any potential things that could help me? Thanks for replying

[Wraith]

Can you access the router from the new computer? What encryption are you using on the router? Can you access the other computers on your network?


Possible solution.
Power down the router (unplug it)
Power down your modem (also unplug)
Wait 3 minutes
Turn on modem
wait for modem to show ready
Turn on router
Try to connect

[lucky.BOY]

I cant acces it from the new one, i am using WPA encryption, and i cant acces the other computers, wich i think was not possible with the old ones... but i have managed to put MAC adress of my new computer into list in router.
The worst problem i have now is that i dont know the password . I didnt construct this network, i was about 11 when it was made by some IT guy, and suprisingly my father have not saved the password . Any ideas of retrieving it?
PS: Odd thing is that i still cant acces the router from laptop...
PPS: Thanks for possible solution, i will try it out. Everything is worth trying now...

EDIT: problem solved, i have phoned that IT guy and he told me the password. Meh. Anyway thx for help Wraith