software firmware update?

[shant]

hello, so i have this wireless DSL router which i had bought from my old isp, but around a year later i changed into another isp but the router won't work, they said the other isp(the one i got the router from) had locked it so that it only works with them...
i have tried to update the frimware but the page where you go to update the firmware is removed, i think they have put their own custom firmware in it...
so what i was wondering is if there is a software that manually updates/replaces the firmware...
if there is, i think the router would work again right?

DSL-2640U wireless G ADSL2+ router (http://www.d-link.co.za/DSL-2640U.php)

[shant]

thanks ill see what i can do :)
ill keep you updated :D

[shant]

i have no idea what these are and how to use them... Open-WRT seems to be compatible with my router but idk how to use

[shant]

ill check, thanks