Modem/ Router's adapters?

My adapter for ZyXel modem just stopped working.. i know its a adapter problem because i used my PSP adapter and then my modem powers up but doesnt work properly (maybe because the psp adapter is of a lower voltage or something) but when i plug in the default ZyXel adapter it just doesnt turn on.. Anyway so where can i buy a new adapter in karachi?

Buying a new adapter isn't that hard, just take your burnt adapter to your neighbourhood electric shop and you'll find the replacement adapter. Other day due to fluctuation some of my adapters including dsl modem adapter got burnt as well.